How long can I stay in China with an American green card?

Although you have an American green card, your nationality is still China, so you are free to take it back to China for how long. However, to maintain the validity of the US green card, you must enter the United States at least once every six months, that is, you can return to China for up to six months, otherwise the US Immigration Service will wonder if you really want to become a permanent resident of the United States. However, if it is really impossible to return to the United States once a year under special circumstances, you can apply for a re-entry permit (valid for 1-2 years) to return to the United States one year later. Of course, if you want to go back and forth to the United States many times a year, there is no problem.

American green card generally refers to American permanent resident card.

The American permanent resident card, also known as the green card, is an identity document used to prove that foreigners have the status of permanent residents in the United States. "Getting a green card" refers to the immigration process of becoming a permanent resident. The legal permanent residency of green card holders is an official immigration benefit, including conditional permission to stay in the United States and get a job. The holder must maintain his permanent resident status, and if he no longer meets certain conditions required by the status, the holder may lose his status.