As of April 1, 2019, two foreigners are not allowed to register their marriage at Civil Affairs offices in China (marriages between a foreigner and Chinese national are still permitted.)  This means that two foreigners can no longer obtain a Chinese marriage certificate.  This new regulation was published on March 29, 2019, and went into effect nationwide as of today.  The details of this announcement can be found here: http://www.mca.gov.cn/article/xw/tzgg/201903/20190300016006.shtml (in Chinese only)  or you can call the Civil Affairs hotline at 962200.  

U.S. citizens contemplating marriage to a Chinese citizen in China should review the following information. This information is given for general background reference only.  You or your fiancée should check with local authorities for any changes that might have been made. Marriages in China are registered according to the laws of China.  U.S. diplomatic and consular officers do not have the authority to perform marriages and are not required to witness the marriages of U.S. citizens that take place overseas. Under the U.S. Constitution, the administration of civil affairs is one of the powers reserved for states.  Thus, as federal government employees, U.S. consular officers are prohibited from usurping this state role. 

Marriages in China are administered by the marriage registration office of the local civil affairs bureau, (民政局Min Zheng Ju) in each jurisdiction.  People planning to marry should visit or call one of these offices for specific information. The appropriate civil affairs office will be the one in the jurisdiction in which the Chinese citizen is registered (the location of their 户口hukou). 

While the minimum age for marriage is generally 20 for women and 22 for men, some civil affairs offices may have a higher minimum age.  Both parties must establish that they are single and free to marry.  If you have been previously married, you will be asked to submit original or certified copies of your final divorce or annulment decrees, or of death certificates, if widowed.  Note that at least one party of a marriage must be a Chinese citizen. The U.S. citizen will usually be asked by the local authorities to submit the following documentation in order to be married: 

-A valid passport with a valid Chinese visa 

-An "affidavit of marriageability." You can get this document at the Embassy or Consulate by swearing or affirming before a Consul that you are legally free to marry. You must make an appointment for a notarial service to get this affidavit, and there is a $50 charge. If either party was previously married, bring a clear photocopy of either the divorce or annulment decree or the death certificate which shows how the marriage ended. If you present an original certified copy with the copy for their review, the Chinese authorities will usually accept the copy.  Hold on to your original documents, since they may be required if you later wish to file an immigrant visa petition for your spouse. Note: In order to complete your affidavit of marriageability correctly, you are highly recommended to bring a photocopy of your Chinese fiancé's ID card (Shen Fen Zheng 身份证). 

-Three photos of the couple, taken together 

-Registration fee 

Questions regarding what documents the Chinese partner must submit should be directed to the local marriage registration office (Hun Yin Deng Ji Chu 婚姻登记处). 

Marriage certificates are usually issued on the same day the registration takes place.  Marriages that are legal in the jurisdiction in which they were performed are legal in the United States.  It is not necessary to register your marriage at the Embassy, Consulate, or in the United States, nor do you need to re-marry in the United States.