It has been three years since I got the American green card. Can I go to America again after I return home?

What kind of green card are you? It's BH. It depends on how long you have been in China. You can come back now, because my friend has returned to China many times, and there is nothing wrong with it. I'm afraid the immigration bureau will randomly check you, so it's in trouble. Maybe he can send you a letter and ask you to take your green card to the immigration office.