4.0 version

1、$(‘#yourButton‘).on(‘click‘, function() {
    $(‘#yourfirstSelect2‘).val(null).trigger("change");
    $(‘#yourSecondSelect2‘).val(null).trigger("change");
    ....
});

2、$(‘#yourButton‘).on(‘click‘, function() {
    $(‘#yourfirstSelect2‘).select2(‘val‘,‘all‘);
    $(‘#yourSecondSelect2‘).select2(‘val‘,‘all‘);
 

    ....
});

3.0 version

$(‘#yourButton‘).on(‘click‘, function() {
    $(‘#yourfirstSelect2‘).select2("val", "");
    $(‘#yourSecondSelect2‘).select2("val", "");
    ....
});
ie/google經測試均可用，其他未測試

clear/reset select2，重置select2，恢復默認