以下是我的項(xiàng)目中的圖標(biāo)更改

.el-tree-node__content{
    height: 35px;
    margin: 10px 0px;
    .el-tree-node__expand-icon {
      padding: 0px;
      margin-right: 20px;
      width: 30px;
      height: 30px;
      content: url("../../../commons/images/*****.png");
    }
    .el-tree-node__expand-icon.expanded{
      transform: rotate(0deg);//不讓旋轉(zhuǎn)
    }
  }
  
  原理同上

這個(gè)要通過CSS強(qiáng)制更改

<div class="el-tree">
    <div class="el-tree-node is-expanded">
        <div class="el-tree-node__content" style="padding-left: 0px;"><span
                class="el-tree-node__expand-icon expanded"></span><!----><!----><span
                class="el-tree-node__label">一級(jí) 1</span></div>
        <div class="el-tree-node__children" data-old-padding-top="" data-old-padding-bottom="" data-old-overflow="">
            <div class="el-tree-node is-expanded is-current">
                <div class="el-tree-node__content" style="padding-left: 16px;"><span
                        class="el-tree-node__expand-icon expanded"></span><!----><!----><span
                        class="el-tree-node__label">二級(jí) 1-1</span></div>
                <div class="el-tree-node__children" data-old-padding-top="" data-old-padding-bottom=""
                     data-old-overflow="">
                    <div class="el-tree-node">
                        <div class="el-tree-node__content" style="padding-left: 32px;"><span
                                class="el-tree-node__expand-icon is-leaf"></span><!----><!----><span
                                class="el-tree-node__label">三級(jí) 1-1-1</span></div>
                        <div class="el-tree-node__children" style="display: none;"></div>
                    </div>
                </div>
            </div>
        </div>
    </div>
</div>

上面是一個(gè)tree渲染后的html代碼，我們可以看到，每一個(gè)節(jié)點(diǎn)有一個(gè).el-tree-node__expand-icon的元素，這就是每個(gè)項(xiàng)的icon，而.el-tree-node__expand-icon.expanded的元素就是激活后的icon。
另外可以看源碼發(fā)現(xiàn)，這些icon都是用css繪制的，加入以下代碼后就可以自定義

//css代碼
.el-tree-node__expand-icon{
    border:0;
    /*自定義，必要時(shí)用!important*/
}
.el-tree-node__expand-icon.expanded{
    /*自定義，必要時(shí)用!important*/
}

.el-tree-node__expand-icon+span::before {
  display: inline-block;
  vertical-align: bottom;
  margin-bottom: -3px;
  width: 20px;
}

.el-tree-node__content{
    .el-tree-node__expand-icon+span::before {
        content: url(..//img/sitemap.png);
    }
  }
.el-tree-node__children{
    .el-tree-node__expand-icon+span::before {
        content: url(..//img/folder.png);
    }
}

圖片描述