效果图如下

<el-table :data="atlasDataList" style="width: 100%" :span-method="spanMethod">
              <el-table-column prop="stationName" label="" width="180" />
              <el-table-column prop="atlasNumber" label="" width="180" />
              <el-table-column prop="atlasName" label="图册名称" width="180" />
            </el-table>
            
<script setup>
    import { objectSpanMethod } from './spanMethod';
    
	//调用合并行的方法
    const spanMethod = ({ row, column, rowIndex, columnIndex }) => {
      if (columnIndex < 2) { // 只合并前两列
        return objectSpanMethod({ row, column, rowIndex, columnIndex }, atlasTypeList.value.length);
      } else {
        return { rowspan: 1, colspan: 1 }; // 不合并其他列
      }
    };
    
	// 合并列的计算方法
	export const objectSpanMethod = ({
                                     row,
                                     column,
                                     rowIndex,
                                     columnIndex,
                                 }, mergeCount) => {
   		 // 每 mergeCount 行合并
   		 if (rowIndex % mergeCount === 0) {
		        return {
		            rowspan: mergeCount,
		            colspan: 1,
		        };
		    } else {
		        return {
		            rowspan: 0,
		            colspan: 0,
		        };
		    }
		};

</script>