<el-form ref="newform" :model="newform" :rules="rules">
    <el-form-item prop="expName" label="">
     <el-input v-model="newform.expName" placeholder="" style="width:75%">
     </el-input>
    </el-form-item>
    <el-form-item prop="expSn" label="">
     <el-input v-model="newform.expSn" placeholder="" style="width:75%">
     </el-input>
    </el-form-item>
    <el-form-item label='' prop="groupName">
     <el-select v-model="newform.groupName" placeholder="" style="width:75%" @change="newSelectGroup($event)">
      <el-option
      v-for="item in groupOptions"
      :key="item.groupId"
      :label="item.groupName"
      :value="item.groupId">
      </el-option>
     </el-select>
    </el-form-item>
    <el-form-item label="" prop="subGroupName">
     <el-select v-model="newform.subGroupName" placeholder="" style="width:75%" @change="newSelectSubGroup($event)">
      <el-option
      v-for="item in subGroupOptions"
      :key="item.subGroupId"
      :label="item.subGroupName"
      :value="item.subGroupId">
      </el-option>
     </el-select>
    </el-form-item>
    <el-form-item label="" prop="expvmDifficulty">
     <el-rate v-model="newform.expvmDifficulty" :max="5" style="line-height: 2;"></el-rate>
    </el-form-item>
    <el-form-item label="" prop="expvmInstruction">
     <el-upload
      class="upload-demo"
      drag
      ref="uploadhtml"
      :action="upload_url"
      :auto-upload="false"
      :before-upload="newHtml"
      accept=".html, .htm">
      <div class="el-upload__text">将文件拖到此处，或<em>点击上传</em></div>
      <div slot="tip" class="el-upload__tip">实验信息上传，只能传(.html/.htm)文件</div>
     </el-upload>
    </el-form-item>
    <el-form-item label="" prop="expvmFiles">
     <el-upload
      class="upload-demo"
      drag
      ref="uploadfile"
      :action="upload_url"
      :auto-upload="false"
      :before-upload="newFiles"
      multiple>
      <div class="el-upload__text">将文件拖到此处，或<em>点击上传</em></div>
      <div slot="tip" class="el-upload__tip">实验信息附件上传，只能传(.file)文件</div>
     </el-upload>
    </el-form-item>
    <el-form-item label="" prop="expvmVideo">
     <el-upload
      class="upload-demo"
      drag
      ref="uploadvideo"
      :action="upload_url"
      :auto-upload="false"
      :before-upload="newVideo"
      accept=".mp4">
      <div class="el-upload__text">将文件拖到此处，或<em>点击上传</em></div>
      <div slot="tip" class="el-upload__tip">实验视频上传，只能传(.mp4)文件</div>
     </el-upload>
    </el-form-item>
    <el-form-item style="text-align:center">
     <el-button type="primary" @click="newSubmitForm()" class="yes-btn">
     确 定
     </el-button>
     <el-button @click="resetForm('newform')">
     重 置
     </el-button>
    </el-form-item>
   </el-form>

data () {
  return {
　　　 upload_url: 'aaa',    // 随便填一个，但一定要有
　　  uploadForm: new FormData(),  // 一个formdata
   rules: {},   // 用到的规则
   newform: {
    expName: '',
    groupName: '',
    expSn: '',
    subGroupName: '',
    expvmDifficulty: 1
   }
  }
 }

newSubmitForm () {
   this.$refs['newform'].validate((valid) => {
    if (valid) {
     this.uploadForm.append('expName', this.newform.expName)
     this.uploadForm.append('expSn', this.newform.expSn)
     this.uploadForm.append('groupId', this.newgroupId)
     this.uploadForm.append('subGroupId', this.newsubgroupId)
     this.uploadForm.append('expvmDifficulty', this.newform.expvmDifficulty)
     
     newExp(this.uploadForm).then(res => {
      if (res.code === 400) {
       this.$message.error(res.error)
      } else if (res.code === 200) {
       this.$message.success('上传成功！')
      
      }
     })
     this.$refs.uploadhtml.submit()  // 提交时触发了before-upload函数
     this.$refs.uploadfile.submit()
     this.$refs.uploadvideo.submit()
     
    } else {
     console.log('error submit!!')
     return false
    }
   })
  },
  newHtml (file) {  // before-upload
   this.uploadForm.append('html', file)
   return false
  },
  newFiles (file) {
   this.uploadForm.append('file[]', file)
   return false
  },
  newVideo (file) {
   this.uploadForm.append('video', file)
   return false
  }
newExp函数是作为一个前后端交互的函数
export function newExp (data) {
 return axios({
  method: 'post', // 方式一定是post
  url: '你的后台接收函数路径',
  timeout: 20000,
  data: data    // 参数需要是单一的formData形式
 })
}

public function newExp() {
   $param = $this->request->post();     // 获取页面表单传值
   $files = $this->request->file();     // 接收到的文件
 }

this.uploadForm.append('file[]', file)