<el-form-item label="注册日期" label-width="210px">
        <el-date-picker clearable
                        v-model="registerTime"
                        type="daterange"
                        range-separator="至"
                        value-format="yyyy-MM-dd"
                        start-placeholder="开始日期"
                        end-placeholder="结束日期">
        </el-date-picker>
      </el-form-item>
      
  <el-form-item>
        <el-button type="primary" icon="el-icon-search" size="mini" @click="handleQuery">搜索</el-button>
        <el-button icon="el-icon-refresh" size="mini" @click="resetQuery">重置</el-button>
      </el-form-item>

/** 重置按钮操作 */
resetQuery() {
  this.registerTime = null;		//核心代码
  //在registerTime 为null后,在刷新表单
  this.$nextTick(() => { //核心代码
    this.resetForm('queryForm')
    this.handleQuery()
  })
},

效果