How to apply long term stay in China?

If you are already married, then you can apply for Q1 type, which enables you to stay for long time. Your invitation letter from your wife, a copy of her Chinese ID card and your marriage certificate are required. And do not forget to have your marriage certificate authenticated at Chinese consulate if you got it in Singapore. After you arrive, you need to have it notarized at local notary office and translate it into Chinese by qualified translation company. Then you can change Q1 into long term reisdent permit.

Duration of stay depends on how rich your wife is because she is the one who supports you. You can't work under Q1 too. According to someone, your wife should at least have 60000 RMB in her account. Then you can get one year resident permit. The more money she has, the longer time you can stay with her in PRC.