• 修改el-transfer 左右两个穿梭框的高度和宽度，具体效果如下
• 正常大小的穿梭框
• 修改之后的，主要在style中加上如下样式即可
  

/deep/ .el-transfer-panel{
width: 470px; /* 左右两个穿梭框的高度和宽度 */
height: 450px;
}
/deep/ .el-transfer-panel__list.is-filterable {
height: 303px; /* 穿梭框列表高度 */
}

• 全部代码如下：

<template>
  <p style="text-align: center; margin: 50px 0 20px">使用 scoped-slot 自定义数据项</p>
  <div style="text-align: center">
    <el-transfer
      style="text-align: left; display: inline-block"
      v-model="value4"
      filterable
      :left-default-checked="[2, 3]"
      :right-default-checked="[1]"
      :titles="['Source', 'Target']"
      :button-texts="['到左边', '到右边']"
      :format="{
        noChecked: '${total}',
        hasChecked: '${checked}/${total}'
      }"
      @change="handleChange"
      :data="data">
      <span slot-scope="{ option }">{{ option.key }} - {{ option.label }}</span>
      <el-button class="transfer-footer" slot="left-footer" size="small">操作</el-button>
      <el-button class="transfer-footer" slot="right-footer" size="small">操作</el-button>
    </el-transfer>
  </div>
</template>

<style>
  .transfer-footer {
    margin-left: 20px;
    padding: 6px 5px;
  }
 /deep/ .el-transfer-panel{
	width: 470px; /* 左右两个穿梭框的高度和宽度 */
	height: 450px;
}
/deep/ .el-transfer-panel__list.is-filterable {
	height: 303px; /* 穿梭框列表高度 */
}
</style>

<script>
  export default {
    data() {
      const generateData = _ => {
        const data = [];
        for (let i = 1; i <= 15; i++) {
          data.push({
            key: i,
            label: `备选项 ${ i }`,
            disabled: i % 4 === 0
          });
        }
        return data;
      };
      return {
        data: generateData(),
        value: [1],
        value4: [1],
        renderFunc(h, option) {
          return <span>{ option.key } - { option.label }</span>;
        }
      };
    },

    methods: {
      handleChange(value, direction, movedKeys) {
        console.log(value, direction, movedKeys);
      }
    }
  };
</script>