Do China people need a visa to travel to China after immigrating to the United States?

If you didn't get a green card until you immigrated to the United States, you are still a citizen of China. You don't need a visa to return to China. You just need to get a China passport and a valid American green card.

If you change your nationality after immigrating to the United States, you are an American, not a citizen of China. In this case, you need to apply for a visa at the local consulate of China in the United States before returning to China.