<el-form-item>
              <el-date-picker v-model="dateRange"
                              suffix-icon="el-icon-date"
                              size="small"
                              style="width: 240px;margin-left:22px;"
                              value-format="yyyy-MM-dd"
                              type="daterange"
                              prefix-icon="prefix-icon-class"
                              range-separator="-"
                              start-placeholder="开始日期"
                              end-placeholder="结束日期" />
            </el-form-item>

在标签中添加 prefix-icon=“prefix-icon-class” 为下面设置样式提供类名

 mounted () {
    document.getElementsByClassName('el-input__icon')[2].classList.remove('el-range__close-icon')
    document.getElementsByClassName('el-input__icon')[2].classList.add('el-icon-date')
  },

.prefix-icon-class {
display: none;
}
.el-input__icon {
/* 移动后的icon高度100%会造成不居中 */
height: 40px;
}