<el-input
  placeholder="输入关键字进行过滤"
  v-model="filterText">
</el-input>

<el-tree
  class="filter-tree"
  :data="data"
  :props="defaultProps"
  default-expand-all
  :filter-node-method="filterNode"
  ref="tree">
</el-tree>

<script>
  export default {
    watch: {
      filterText(val) {
        this.$refs.tree.filter(val);
      }
    },

    methods: {
      filterNode (value, data, node) {
        return this.filterNodeAndParent(value, data, node)
      },

      // 递归检测父元素或自己是否符合条件
      filterNodeAndParent (value, data, node) {
        if (node.level === 1) {
          return node.data.label.indexOf(value) !== -1
        } else if (data.level !== 1) {
          // 判断自己是否符合条件
          if (node.data.label.indexOf(value) !== -1) {
            return true
          } else { // 否则查找父级
            return this.filterNodeAndParent(value, node.data, node.parent)
          }
        }
      }
    },

    data() {
      return {
        filterText: '',
        data: [{
          id: 1,
          label: '一级 1',
          children: [{
            id: 4,
            label: '二级 1-1',
            children: [{
              id: 9,
              label: '三级 1-1-1'
            }, {
              id: 10,
              label: '三级 1-1-2'
            }]
          }]
        }, {
          id: 2,
          label: '一级 2',
          children: [{
            id: 5,
            label: '二级 2-1'
          }, {
            id: 6,
            label: '二级 2-2'
          }]
        }, {
          id: 3,
          label: '一级 3',
          children: [{
            id: 7,
            label: '二级 3-1'
          }, {
            id: 8,
            label: '二级 3-2'
          }]
        }],
        defaultProps: {
          children: 'children',
          label: 'label'
        }
      };
    }
  };
</script>

原文链接：https://juejin.cn/post/6911992646563004429