回答

wxml

<view>
         <picker mode="multiSelector" bindchange="bindMultiPickerChange" 
              bindcolumnchange="bindMultiPickerColumnChange" value="{{multiIndex}}" range="{{multiArray}}">
                <view class="picker">{{multiArray[1][multiIndex[1]]}}▼</view>
         </picker>
</view>

Page({
    data: {
        multiArray: [['类别1', '类别2'], ['a', 'b'],],
        multiIndex: [0, 0],
        subclass=[['a', 'b','c'], ['d', 'e','f'],],
    },
    // 所有行业
    bindMultiPickerChange: function (e) {
        //console.log('picker发送选择改变，携带值为', e.detail.value)
        this.setData({
            multiIndex: e.detail.value
        })
    },
    bindMultiPickerColumnChange: function (e) {
        //console.log('修改的列为', e.detail.column, '，值为', e.detail.value);
        var multiArray = this.data.multiArray,
            multiIndex = this.data.multiIndex,
            subclass= this.data.subclass;
        // console.log(e.detail)
        multiIndex[e.detail.column] = e.detail.value;
        if(e.detail.column==0) {
           
             multiArray[1] = subclass[e.detail.value];
                      
        }
        //console.log(data.multiIndex);
        this.setData({
            multiArray,
            multiIndex
        }
        );
    }
    }）