wxml;

<picker name="create_id" mode="multiSelector" bindchange="bindMultiPickerChange" bindcolumnchange="bindGradeChange" value="{{multiIndex}}" range="{{multiArray}}" range-key="{{'title'}}">
<view class='pick-content'>
<text>{{multiArray[0][multiIndex[0]].title}}，{{multiArray[1][multiIndex[1]].title}}，{{multiArray[2][multiIndex[2]].title}}</text>
</view>
</picker>

js

bindMultiPickerChange: function (e) {
this.setData({
multiIndex: e.detail.value
})
},
bindGradeChange(e) {
console.log('修改的列为', e.detail.column, '，值为', e.detail.value);
let data = {
multiArray: this.data.multiArray,
multiIndex: this.data.multiIndex
}
data.multiIndex[e.detail.column] = e.detail.value
if (e.detail.column == 0) {
var grade = this.data.multiArray[0][data.multiIndex[0]];
data.multiArray[1] = this.data.allGrade[grade.id].teams
data.multiIndex[1] = 0;
var classes = data.multiArray[1][0];
let arr = this.data.allStudents[classes.id] ? this.data.allStudents[classes.id] : [];
data.multiArray[2] = arr
data.multiIndex[2] = 0
} else if (e.detail.column == 1) {
var classes = this.data.multiArray[1][data.multiIndex[1]];
let arr = this.data.allStudents[classes.id] ? this.data.allStudents[classes.id] : [];
data.multiArray[2] = arr
data.multiIndex[2] = 0
}
this.setData(data);
},

数据格式（以年级为例）

[ {
title: '一年级',
id: 1
}, {
title: '二年级',
id: 2
}, {
title: '三年级',
id: 3
}, {
title: '四年级',
id: 4
}, {
title: '五年级',
id: 5
}, {
title: '六年级',
id: 6
}
]

效果