解决方法，判断状态码，上传组件upload绑定ref为refName

  <el-upload
                  class="upload-demo"
                  action="/api/imageInfo/uploadFiles"
                  :data="uploadData"
                  :on-success="(res) => UploadFilesSuccess(res, item)"
                  :on-remove="(file) => UploadFilesRemove(item, file, fileList)"
                  :file-list="fileList"
                  :before-upload="beforeUpload"
                  drag
                  ref="refName"   //****
                >
                  <div class="el-upload__text">
                    <i class="el-icon-upload"></i> 将文件拖到此处，或<em
                      >点击上传</em
                    >
                  </div>
                </el-upload>

this.$refs.refName[0].uploadFiles.splice(
          this.$refs.refName[0].uploadFiles.indexOf(item),
          1
        );

因为我的数据是数组循环出来的所以refName后面跟了下标，正常的就是this…$refs.refName.uploadFiles就可以