1、设置属性：@selection-change=“handleSelectionChange”

<el-table
    :data="taskList"
    ref="tableDataRefs"
    @selection-change="handleSelectionChange"
    :header-cell-class-name="hideAllCheckbox"
  >

function handleSelectionChange(selection) {
  if (selection.length > 1) {
    // 如果选择了多个，只保留最后一个
    selectedRow.value = selection[selection.length - 1];
    let del_row = selection.shift();
    // 其余的都不选中
    tableDataRefs.value.toggleRowSelection(del_row, false);
  } else {
    selectedRow.value = selection.length ? selection[0] : null;
  }
}

2、使用动态css 隐藏顶部全选框。添加属性：:header-cell-class-name=“hideAllCheckbox”

function hideAllCheckbox({ row, column, rowIndex, columnIndex }) {
  if (columnIndex === 0) return "setDisable";
}

<style lang="scss" scoped>
:deep(.setDisable) {
  .cell {
    visibility: hidden;
  }
}
</style>