效果展示：

  <el-table style="height: 500px;" :data="tableData" border empty-text="暂无数据" v-loading="loading":header-cell-style="{ 'text-align': 'center' }" :cell-style="{ 'text-align': 'center' }" show-overflow-tooltipref="multipleTable" @select="handleSelection" @select-all="handleCount"><el-table-column type="selection" width="40" fixed="left" />
</el-table>

// 多选
const checkId = ref([]);  
const multipleTable = ref()
// 手动勾选单选的情况
const handleSelection = (val) => {if (checkId.value.length > val.length) {// 取消选中let checkAll = checkId.value;checkId.value = val;checkAll.forEach((item) => {let v = val.find(i => i.qdfphm === item.gl_qdfphm);  //关联的条件if (v === undefined && item.gl_qdfphm != '') {multipleTable.value.toggleRowSelection(item, false);checkId.value = val.filter(v => item.id != v.id)}})} else {// 选中checkId.value = val;let v = val[val.length - 1];if (v.gl_qdfphm != '') {let vv = tableData.value.find(item => item.qdfphm == v.gl_qdfphm)  //关联的条件multipleTable.value.toggleRowSelection(vv, true);checkId.value.push(vv);}}if (chooseTab.value == 1) {badgeTotal.value.total_supply = checkId.value.length} else if (chooseTab.value == 2) {badgeTotal.value.total_delete = checkId.value.length}
}
// 手动勾选全选情况(计算总数)
const handleCount = (val) => {checkId.value = val;
}

总结：重点在toggleRowSelection（）方法