效果图：
html：

<el-input
   v-model="searchVal"
   placeholder="请输入关键词"
   clearable
   style="margin-bottom: 12px"
 />
 <div class="treeBox">
   <el-tree
     :data="sourceData"
     node-key="id"
     default-expand-all
     :expand-on-click-node="false"
     :props="defaultProps"
     @node-click="handleNodeClick"
   >
   	 // 重点：给节点添加图标
     <span slot-scope="{ node, data }" class="slot-t-node">
       <template>
         <i
           :class="{
             'el-icon-folder': !node.expanded,       // 节点收缩时的图标
             'el-icon-folder-opened': node.expanded, // 节点展开时的图标
             'el-icon-user-solid': data.type === 2   // data.type是后端配合提供的识别字段，最后一级
           }"
           style="color: #409eff;" // 图标颜色
         />
         <span>{{ node.label }}</span>
       </template>
     </span>
   </el-tree>
 </div>

js:

data() {
    return {
      searchVal: '', // 输入的关键词
      defaultProps: {
        children: 'childrenList', // 将tree中的每项的 childrenList 映射为 children
        label: 'name' // 将tree中的每项的 name 映射为 label
      },
      sourceData: [ // 树源数据
        {
          id: null,
          name: '深圳市XXX有限公司',
          parentId: '0',
          childrenList: [
            {
              id: null,
              name: '研发中心',
              parentId: '1',
              childrenList: [
                {
                  id: null,
                  name: '研发1组',
                  parentId: '2',
                  childrenList: [
                    {
                      id: null,
                      name: 'IOS测试机',
                      parentId: null,
                      childrenList: null,
                      type: 2
                    }
                  ],
                  type: 1
                },
                {
                  id: null,
                  name: '安卓测试机',
                  parentId: null,
                  childrenList: null,
                  type: 2
                }
              ],
              type: 1
            },
            {
              id: null,
              name: '产品中心',
              parentId: '1',
              childrenList: [],
              type: 1
            },
            {
              id: null,
              name: '员工1',
              parentId: null,
              childrenList: null,
              type: 2
            },
            {
              id: null,
              name: '员工12',
              parentId: null,
              childrenList: null,
              type: 2
            },
            {
              id: null,
              name: '员工13',
              parentId: null,
              childrenList: null,
              type: 2
            }
          ],
          type: 1
        }
      ]
    }
  },
  methods: {
  	// 节点点击时
    handleNodeClick(data) {
      // 。。。
    }
  }