How long can an American green card stay in China, six months or three months?

The American green card generally refers to the American permanent resident card, and the return to China does not exceed 1 year.

According to the immigration law of the United States, permanent residents must use a valid immigration visa and a valid home country passport to enter the United States, otherwise they are not allowed to enter the country. After having an American green card, as long as you leave the United States for less than one year, the green card itself can be regarded as a valid entry immigrant visa, and you don't need to apply for a visa at the American embassy or consulate. If you leave the United States for more than one year, you must apply for a re-entry visa before you can leave the country. As a valid immigrant visa, the re-entry visa is valid for up to two years. Cardholders who have not entered the United States for more than a period of time are likely to lose their permanent residency when they enter the country, because the immigration law requires green card holders to leave the United States only temporarily.

See Baidu Encyclopedia:/view/view1822437.htm.