效果图：

封装组件：TreeSelect.vue

<!--
    /**
     * 下拉选择树形组件，下拉框展示树形结构，提供选择某节点功能，方便其他模块调用
     * @date 2020-12-09
     * 调用示例：
     * <tree-select :height="400" // 下拉框中树形高度
     *              :width="200" // 下拉框中树形宽度
     *              :data="data" // 树结构的数据
     *              :defaultProps="defaultProps" // 树结构的props
     *              multiple   // 多选
     *              :rootNodeChick="true" // 是否可以选择根节点。默认 false ture 为可选。false 为不可选
     *              checkStrictly // 多选时，严格遵循父子不互相关联
     *              :nodeKey="nodeKey"   // 绑定nodeKey，默认绑定'id'
     *              :checkedKeys="defaultCheckedKeys"  // 传递默认选中的节点key组成的数组
     *              @popoverHide="popoverHide"> // 事件有两个参数：第一个是所有选中的节点ID，第二个是所有选中的节点数据
     *              </tree-select>
     *
     * import TreeSelect from "@/utils/components/tree-select.vue";
     * components: { TreeSelect },
     *
     *数据格式
     *let obj = {
                "id": "10",
                "label": "琼瑶作品集",
                "children": [],
                  };
     * 清空树的选中状态。只需要将clear 从 0 累加就可以。这里是监听的数据改变状态。不为 0 则清空数据。Number类型
     */
-->
<template>
  <div style="width:284px;display: inline-block;margin-left: -5px">
    <!-- <div class="mask"
         v-show="isShowSelect"
         @click="isShowSelect = !isShowSelect"></div> -->
    <el-popover placement="bottom-start"
                :width="width"
                trigger="manual"
                v-model="isShowSelect"
                @hide="popoverHide"
                clearable>
      <el-tree class="common-tree"
               :style="style"
               clearable
               ref="tree"
               :data="data"
               :props="defaultProps"
               :show-checkbox="multiple"
               :node-key="nodeKey"
               :check-strictly="checkStrictly"
               default-expand-all
               :expand-on-click-node="false"
               :default-checked-keys="defaultCheckedKeys"
               :highlight-current="true"
               @node-click="handleNodeClick"
               @check-change="handleCheckChange"></el-tree>
      <el-select :style="selectStyle"
                 slot="reference"
                 ref="select"
                 v-model="selectedData"
                 :multiple="multiple"
                 collapse-tags
                 clearable
                 @click.native="isShowSelect = !isShowSelect"
                 class="tree-select">
        <el-option v-for="item in options"
                   :key="item.value"
                   :label="item.label"
                   :value="item.value"></el-option>
      </el-select>
    </el-popover>
  </div>
</template>
 
<script>
export default {
  name: "tree-select",
  // props: ["clear"],
  props: {
    // 树结构数据
    data: {
      type: Array,
      default () {
        return [];
      }
    },
    // 是否可选根节点
    rootNodeChick: Boolean,
    // 是否清空数据
    clear: Number,
    defaultProps: {
      type: Object,
      default () {
        return {};
      }
    },
    // 配置是否可多选
    multiple: {
      type: Boolean,
      default () {
        return false;
      }
    },
    nodeKey: {
      type: String,
      default () {
        return "id";
      }
    },
    // 显示复选框情况下，是否严格遵循父子不互相关联
    checkStrictly: {
      type: Boolean,
      default () {
        return false;
      }
    },
    // 默认选中的节点key数组
    checkedKeys: {
      type: Array,
      default () {
        return [];
      }
    },
    width: {
      type: Number,
      default () {
        return 260;
      }
    },
    height: {
      type: Number,
      default () {
        return 360;
      }
    },
  },
  data () {
    return {
      defaultCheckedKeys: [],
      isShowSelect: false, // 是否显示树状选择器
      options: [],
      selectedData: [], // 选中的节点
      style: "width:" + this.width + "px;" + "height:" + this.height + "px;",
      selectStyle: "width:" + (this.width + 24) + "px;",
      checkedIds: [],
      checkedData: []
    };
  },
  mounted () {
    if (this.checkedKeys.length > 0) {
      if (this.multiple) {
        this.defaultCheckedKeys = this.checkedKeys;
        this.selectedData = this.checkedKeys.map(item => {
          var node = this.$refs.tree.getNode(item);
          return node.label;
        });
      } else {
        var item = this.checkedKeys[0];
        this.$refs.tree.setCurrentKey(item);
        var node = this.$refs.tree.getNode(item);
        this.selectedData = node.label;
      }
    }
  },
  methods: {
    loadCheckedKeys () {
      if (this.checkedKeys.length > 0) {
        if (this.multiple) {
          this.defaultCheckedKeys = this.checkedKeys;
          this.selectedData = this.checkedKeys.map(item => {
            var node = this.$refs.tree.getNode(item);
            return node.label;
          });
        } else {
          var item = this.checkedKeys[0];
          this.$refs.tree.setCurrentKey(item);
          var node = this.$refs.tree.getNode(item);
          this.selectedData = node.label;
        }
      }
    },
    changeIsShowSelect () {
      this.isShowSelect = false;
    },
    popoverHide () {
      if (this.multiple) {
        this.checkedIds = this.$refs.tree.getCheckedKeys(); // 所有被选中的节点的 key 所组成的数组数据
        this.checkedData = this.$refs.tree.getCheckedNodes(); // 所有被选中的节点所组成的数组数据
      } else {
        this.checkedIds = this.$refs.tree.getCurrentKey();
        this.checkedData = this.$refs.tree.getCurrentNode();
      }
      this.$emit("popoverHide", this.checkedIds, this.checkedData);
    },
    // 节点被点击时的回调,返回被点击的节点数据
    handleNodeClick (data, node) {
      if (!this.multiple) {
        let tmpMap = {};
        tmpMap.value = node.key;
        tmpMap.label = node.label;
        this.options = [];
        this.options.push(tmpMap);
        this.selectedData = node.label;
        this.isShowSelect = !this.isShowSelect;
      }
    },
    // 节点选中状态发生变化时的回调
    handleCheckChange () {
      var checkedKeys = this.$refs.tree.getCheckedKeys(); // 所有被选中的节点的 key 所组成的数组数据
      this.options = [];
      if (!this.rootNodeChick)
        checkedKeys.forEach(item => {
          var node = this.$refs.tree.getNode(item); // 所有被选中的节点对应的node
          let tmpMap = {};
          if (node.childNodes.length == 0) {
            tmpMap.value = node.key;
            tmpMap.label = node.label;
            this.options.push(tmpMap);
          }
        });
      else
        this.options = checkedKeys.map(item => {
          var node = this.$refs.tree.getNode(item); // 所有被选中的节点对应的node
          let tmpMap = {};
          tmpMap.value = node.key;
          tmpMap.label = node.label;
          return tmpMap;
        });
      this.selectedData = this.options.map(item => {
        return item.label;
      });
    }
  },
  watch: {
    isShowSelect (val) {
      // 隐藏select自带的下拉框
      this.$refs.select.blur();
    },
    clear: function (n, o) {
      //箭头函数  不然会发生this改变
      if (n != 0) {
        this.selectedData = [];
        this.$nextTick(() => {
          this.$refs.tree.setCheckedKeys([]);
        });
      }
    },
    selectedData: function (newData, oldData) {
      this.popoverHide();
      if (
        newData == undefined ||
        newData == null ||
        newData == [] ||
        newData.length == 0
      )
        this.$refs.tree.setCheckedKeys([]);
    }
  }
};
</script>
 
<style scoped>
.mask {
  width: 100%;
  height: 100%;
  position: fixed;
  top: 0;
  left: 0;
  opacity: 0;
  z-index: 999;
}
.common-tree {
  overflow: auto;
}
</style>
 
<style>
.tree-select .el-select__tags .el-tag .el-tag__close {
  display: none;
}
.tree-select .el-select__tags .el-tag .el-icon-close {
  display: none;
}
</style>

 调用：

import TreeSelect from "./TreeSelect";//改为自己的路径
export default {
  components: { TreeSelect },
  data () {
    return {
      //下拉树
      isShowSelect: false,//选择面板，默认隐藏
      officeTreeList: [],//树形结构数据
      selectedOfficeIds: '',//选择后返回的选中id，以逗号拼接
      selectedOffices: [],//选择后返回的选中对象，
      clearTreeSelect: 0,
      defaultProps: {
        children: "children",//树形结构数据中对应的属性名称，可改为自己数据中属性
        label: "label"//树形结构数据中对应的属性名称，可改为自己数据中属性
      },
      nodeKey: "id",//树形结构数据中对应的属性名称，可改为自己数据中属性
      defaultCheckedKeys: [],//默认初次选中的数据
      
    }
}

页面：

 <tree-select ref="treeSelect"
                       :data="officeTreeList"
                       placeholder="请选择"
                       :defaultProps="defaultProps"
                       @parent-event="popoverHide"
                       multiple
                       :clear="clearTreeSelect"
                       :nodeKey="nodeKey"
                       :checkedKeys="defaultCheckedKeys"
                       @popoverHide="popoverHide">
          </tree-select>

methods：

 popoverHide (checkedIds, checkedData) {
      this.selectedOfficeIds = checkedIds;
      //this.selectedOffices = checkedData;//此数据没大用，可注释
      //if (checkedData != undefined && checkedData != null) {
        //checkedData.forEach(item => {
          //if (item.children == undefined || item.children == null) {
            //this.selectedOffices.push(item.id);
          //}
        //});
      //}
    },

在父组件的最外层div上加个@click="divClick”事件，控制选择面板的显隐：

 divClick () {
      this.$nextTick(() => {
        this.$refs.treeSelect.changeIsShowSelect();
      })
    },

附加说明：

//数据加载完成后，（以下是树形结构）
this.officeTreeList=[
{
          "id": "0",
          "label": "作品分类",
          "icon": "offices",
          "url": null,
          "state": "open",
          "children": [
            {
              "id": "o58",
              "label": "金庸作品集",
              "icon": "fold",
              "url": null,
              "state": "open",
              "children": [
                {
                  "id": "o62",
                  "label": "武侠类",
                  "icon": "fold",
                  "url": null,
                  "state": "open",
                  "children": [
                    {
                      "id": "o103",
                      "label": "天龙八部",
                      "icon": "office",
                      "url": null,
                      "state": "open",
                      "children": [],
                      "levelId": 0,
                      "parentId": "o62",
                      "role": null,
                      "selectNode": null,
                      "params": null,
                      "disabled": false,
                      "message": null,
                      "remarkMap": null
                    },
                    {
                      "id": "o104",
                      "label": "射雕英雄传",
                      "icon": "office",
                      "url": null,
                      "state": "open",
                      "children": [],
                      "levelId": 0,
                      "parentId": "o62",
                      "role": null,
                      "selectNode": null,
                      "params": null,
                      "disabled": false,
                      "message": null,
                      "remarkMap": null
                    }
                  ],
                  "levelId": 0,
                  "parentId": "o58",
                  "role": null,
                  "selectNode": null,
                  "params": null,
                  "disabled": false,
                  "message": null,
                  "remarkMap": null
                }
              ],
              "levelId": 0,
              "parentId": "0",
              "role": null,
              "selectNode": null,
              "params": null,
              "disabled": false,
              "message": null,
              "remarkMap": null
            },
            {
              "id": "o110",
              "label": "古龙作品集",
              "icon": "fold",
              "url": null,
              "state": "open",
              "children": [
                {
                  "id": "o59",
                  "label": "绝代双骄",
                  "icon": "office",
                  "url": null,
                  "state": "open",
                  "children": [],
                  "levelId": 0,
                  "parentId": "o110",
                  "role": null,
                  "selectNode": null,
                  "params": null,
                  "disabled": false,
                  "message": null,
                  "remarkMap": null
                },
                {
                  "id": "o60",
                  "label": "楚留香传奇",
                  "icon": "office",
                  "url": null,
                  "state": "open",
                  "children": [],
                  "levelId": 0,
                  "parentId": "o110",
                  "role": null,
                  "selectNode": null,
                  "params": null,
                  "disabled": false,
                  "message": null,
                  "remarkMap": null
                }
              ],
              "levelId": 0,
              "parentId": "0",
              "role": null,
              "selectNode": null,
              "params": null,
              "disabled": false,
              "message": null,
              "remarkMap": null
            },
            {
              "id": "o107",
              "label": "琼瑶作品集",
              "icon": "office",
              "url": null,
              "state": "open",
              "children": [],
              "levelId": 0,
              "parentId": "0",
              "role": null,
              "selectNode": null,
              "params": null,
              "disabled": false,
              "message": null,
              "remarkMap": null
            }
          ],
          "levelId": 0,
          "parentId": null,
          "role": null,
          "selectNode": null,
          "params": null,
          "disabled": false,
          "message": null,
          "remarkMap": null
        }
];
 this.defaultCheckedKeys.push('o60');//默认选中楚留香传奇
 this.$nextTick(() => {
          this.$refs.treeSelect.loadCheckedKeys();
      })
this.selectedOfficeIds = ['o60'];//第一次手动放进去，以后就直接用这个变量即可

感谢文章：https://blog.csdn.net/qq_32786139/article/details/108345247