比如我们获取的字符串是：[{"CityId":18,"CityName":"西安","ProvinceId":27,"CityOrder":1},{"CityId":53,"CityName":"广州","ProvinceId":27,"CityOrder":1}]

可以通过eval处理：

var data;var json='[{"CityId":18,"CityName":"西安","ProvinceId":27,"CityOrder":1},{"CityId":53,"CityName":"广州","ProvinceId":27,"CityOrder":1}]';eval("data="+json);

获取其中的值：

$.each(data,function(index, value){    alert(value.CityName);})