Do I have to show my green card and China passport when entering or leaving the country?

Yes, you need a valid immigrant visa and a valid national passport.

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.

Extended data:

Entry and exit requirements:

1, China citizens leaving or entering the country shall submit their passports or other travel documents and other entry and exit documents to the entry-exit frontier inspection authorities, and can only leave or enter the country after going through the prescribed procedures.

2. China citizens who have settled abroad who wish to return to China to settle down shall apply to the people of China, China's embassies and consulates abroad or other overseas institutions entrusted by the Ministry of Foreign Affairs before entering the country, or they may apply to the overseas Chinese affairs department of the local people's government at or above the county level through their relatives.

3. If China citizens who have settled abroad need to provide identification when handling financial, educational, medical, transportation, telecommunications, social insurance, property registration and other affairs in China, they can use their passports to prove their identity.

Baidu Encyclopedia-American Green Card