1.在data中定义变量 expandedIndex，默认展开第一条

expandedIndex:0,

2.标题栏展开、收起显示判断，并填加点击事件 toggleVisibility

     <h5 class="titleLine">{{item.checkPart}}  <span @click="toggleVisibility(index)">{{expandedIndex === index ? '收起' : '展开'}}</span></h5>

3.要展开收起的div处加显示、隐藏判断

  <div class="checkbox"  v-show="expandedIndex === index">
              <el-form-item label="检查时间"  >
                <el-input
                  v-model="item.checkTime"
                  placeholder="请输入检查时间"
                  clearable
                  disabled
                  size="small"
                />
              </el-form-item>
     </div>

4.点击事件 toggleVisibility 逻辑处理

toggleVisibility(index) {
        if (this.expandedIndex === index) {
          this.expandedIndex = null; // 收起当前展开的模块
        } else {
          this.expandedIndex = index; // 展开点击的模块
        }
      },

效果如下图