married at china. What should i do and what document i need?

Jimmy, you should first prepare the necessary documents. For you, the documents include passport, Chinese Visa or residence permit, and a single status certificate issued Malaysian embassy in PRC. For your girlfriend, she should prepare her household registration book, ID card, and single status certificate issued by a local government. After all the documents are ready, you should go together to the local Civil Affairs Department to register your marriage.