<el-upload
            class="upload-demo"
            drag
            multiple
            action="string"
            :on-preview="handlePreview"
            :on-remove="handleRemove"
            :http-request="uploadFile"
            :file-list="form.files">
            <i class="el-icon-upload"></i>
            <div class="el-upload__text">将文件拖到此处，或<em>点击上传</em></div>
            <div slot="tip" class="el-upload__tip">可上传多个文件</div>
          </el-upload>

      //文件列表
      fileLists:[],

// 移除文件
    handleRemove(file, fileList) {
      console.log(file, fileList);
      for (let i = 0; i < this.form.files.length; i++) {
        const ele = this.form.files[i];
        if(ele.url = file.url){
          this.form.files.splice(i,1);
        }
      }
    },
// 在线查看，可下载文件
    handlePreview(file) {
      console.log(file);
      document.location.href = file.url
    },
    // 上传文件方法
    uploadFile(param){
      const formData = new FormData()
      formData.append('file', param.file)
      uploadAvatar(formData).then(response => {
        console.log('上传文件成功')
        var fileObj = {'name':response.name,'url':process.env.VUE_APP_BASE_API + response.imgUrl}
        this.fileLists.push(fileObj)
        this.form.files = this.fileLists;
        // this.form.picUrl = process.env.VUE_APP_BASE_API + response.imgUrl
      }).catch(response => {
        console.log('文件上传失败')
      })
    },

上传文件跨域，以及uploadAvatar方法详情见 https://blog.csdn.net/qq_29384639/article/details/103619259