Mr.steven, you don't need to cancel your Z visa which is still valid, you'd better apply for Z visa even though your present Z visa expires because Z visa holders can apply for residence permit after entry and you can stay in China for a long time. Married to a Chinese citizen doesn't mean that you are automatically permitted to stay in China legally, you have to apply for a valid China visa to enter China. You can apply for L visa for family visit, but the visa stay validity is generally 30 days - 180 days at most per entry. Z visa (then change into residence permit after entry)can permits you stay in China for a longer period.