https://developers.weixin.qq.com/miniprogram/dev/component/picker.html
<picker mode="region" level="city" bindchange="bindRegionChange" style="flex: 1;" value="{{region}}" >
<view class="data" >
<input type="text" placeholder="点击选择省市" disabled="true" value="{{form.province+' '+form.city+' '+form.area}}"/>
<image class="icon" src="/images/icon-right.png"></image>
</view>
</picker>
请具体描述问题出现的流程，并提供能复现问题的简单代码片段（https://developers.weixin.qq.com/miniprogram/dev/devtools/minicode.html）。
打印一下，看看区域是不是undefined
bindRegionChange:function(e) {
var form = this.data.form;
form.province = e.detail.value[0] ;
form.city = e.detail.value[1];
form.area = e.detail.value[2] ;
this.setData({
region:e.detail.value,
form:form
})
},