解决方法：

1、

<el-dialog
  title="提示"
  :visible.sync="channelBox"
  size="tiny"
  :before-close="closeImport ">
  <span>这是一段信息</span>
  <span slot="footer" class="dialog-footer">
    <el-button @click="dialogVisible = false">取 消</el-button>
    <el-button type="primary" @click="dialogVisible = false">确 定</el-button>
  </span>
</el-dialog>

js 

closeImport () {
        this.$refs.publicimport.channelName = ''
        this.channelBox = false
      },

记得取消按钮，也要写这个事件。

2、https://blog.csdn.net/qq_37104276/article/details/78739832