1.打开访达，使用command+shift+g前往/etc路径
2.找到hosts文件，复制一份到桌面
3.添加以下内容到文件中

# GitHub Start 
140.82.113.3      github.com
140.82.114.20     gist.github.com

151.101.184.133    assets-cdn.github.com
151.101.184.133    raw.githubusercontent.com
199.232.28.133     raw.githubusercontent.com 
151.101.184.133    gist.githubusercontent.com
151.101.184.133    cloud.githubusercontent.com
151.101.184.133    camo.githubusercontent.com
199.232.96.133     avatars.githubusercontent.com
151.101.184.133    avatars0.githubusercontent.com
199.232.68.133     avatars0.githubusercontent.com
199.232.28.133     avatars0.githubusercontent.com 
199.232.28.133     avatars1.githubusercontent.com
151.101.184.133    avatars1.githubusercontent.com
151.101.108.133    avatars1.githubusercontent.com
151.101.184.133    avatars2.githubusercontent.com
199.232.28.133     avatars2.githubusercontent.com
151.101.184.133    avatars3.githubusercontent.com
199.232.68.133     avatars3.githubusercontent.com
151.101.184.133    avatars4.githubusercontent.com
199.232.68.133     avatars4.githubusercontent.com
151.101.184.133    avatars5.githubusercontent.com
199.232.68.133     avatars5.githubusercontent.com
151.101.184.133    avatars6.githubusercontent.com
199.232.68.133     avatars6.githubusercontent.com
151.101.184.133    avatars7.githubusercontent.com
199.232.68.133     avatars7.githubusercontent.com
151.101.184.133    avatars8.githubusercontent.com
199.232.68.133     avatars8.githubusercontent.com
199.232.96.133     avatars9.githubusercontent.com
199.232.96.133     avatars.githubusercontent.com

# GitHub End

4.把修改好的文件直接拖回原路径，然后点击鉴定，按下指纹或者输下密码，再选择替换
5.重新打开github，图片可以显示了

windows用户也是一样的，添加以上内容到hosts文件中，只是之前的这部分操作跟mac不一样，百度一下应该都有解答