效果图如下：

表格代码如下：

<el-table 
    width="100%"
    ref="tableRef" 
    style="margin-bottom: 15px;"
    :data="jlData"
    class="tableHeader6"
    header-row-class-name="headerStyleTr6"
    :row-class-name="tableRowClassName"
    show-summary
    :span-method="arraySpanMethod"
    >
        <el-table-column prop="staff_name" label="姓名"></el-table-column>
        <el-table-column prop="staff_id" label="工号"></el-table-column>
        <el-table-column prop="syjlTotal" label="使用量"></el-table-column>
        <el-table-column min-width="125px" prop="xzjlTotal" label="处理报告下载量"></el-table-column>
        <el-table-column min-width="125px" prop="cxbgTotal" label="撤销报告下载量"></el-table-column>
        <el-table-column min-width="110px" prop="lyTotal" label="录音下载量"></el-table-column>
</el-table>

const arraySpanMethod = ({ row, column, rowIndex, columnIndex }:any)=> {
		     nextTick(()=>{
		          if(tableRef.value.$el){
		              let current = tableRef.value.$el.querySelector(".el-table__footer-wrapper").querySelector(".el-table__footer")
		              // cell[0].innerHTML = '合计数'  修改文本
		              let cell = current.rows[0].cells
		              cell[0].style.textAlign = "center"; // 合计行第一列字段居中显示。
		              cell[1].style.display = "none"; // 隐藏被合并的单元格，不隐藏的话还会占着位置。
		              cell[0].colSpan = "2"; // 合并单元格个数
		              console.log(cell,'cell')
		              
		              //修改单元格的样式
		              for(let i=0;i<cell.length;i++){
		                  console.log(cell[i])
		                  if(i==0){
		                      cell[i].style.color = 'red'
		                  }else{
		                      cell[i].style.color = 'orange'
		                  }
		                  
		              }
		          }
		      })
    }