SOURCE

xmSelect.render({
    el: '#province',
    data(){
        return ['北京', '河北'].map((item, index) => ({
           name: item,
           value: index, 
        }))
    },
    on({ arr, change, isAdd }){
        if(isAdd){
            var first = change[0];
            var cityData = [1,2,3].map((item, index) => ({
                name: first.name + item,
                value: index
            }))
            city.update({
                data: cityData,
                paging: true,
            })
        }else{
            city.update({
                paging: false,
                data: []
            })
        }
    }
})

var city = xmSelect.render({
    el: '#city',
    paging: false,
    pageSize: 1,
})

<div id="province"></div>
<div id="city"></div>

#province, #city{
    margin: 20px;
    width: 300px;
    display: inline-block;
}