After a certificate of marriageability has been obtained you must go to the city or town that your Chinese partner’s hukou is registered at, and apply for a marriage certificate. If this is outside of the city of the embassy/consulate that issued your certificate of marriageability then this means you will have to do some traveling. In your partner’s hometown you must go to the local government office that registers marriages, which in a small town would be the minzhengju and in a larger city the minzhengting. In the past both partners had to undertake a medical examination before a certificate of marriage was issued, but this is no longer necessary in most areas. Remember that, typically, marriage registration offices are only open Monday to Friday during certain hours, and are closed Saturday, Sunday and holidays. At the marriage registration office you and your partner will be asked to present the certificate of marriageability and three formal photos of the two of you together, to answer a few simple questions and required to fill out some forms. The final act is for each partner to read a form and swear under oath. One marriage certificate will then be issued to each partner in the form of a red booklet with the couple’s picture inside. The entire process should only take about an hour and the cost is quite cheap, only a few dozen renminbi or less. It is customary to wear informal dress when applying; even jeans and a t-shirt will do. Don’t worry, your new Chinese husband or wife will certainly insist on having an expensive and elaborate wedding on a later date.

Source: http://wikitravel.org/en/Marriage_in_China