If i marry with chinese girl in china, then cancel pakistan nationalty

According to what I know, it's very hard to get the PRC nationality, even though you married a Chinese citizen. To get the PRC nationality, you should first get the permanent residence card of China, which requires you to be married with your wife for at least five years. The applicant should also has lived in China for five consecutive years and shall live in China no less than nine months every year with financial guarantee for living and a residence. So you can see, you can't apply for it at present.