Consult graduate students and immigrants in the United States.

A green card is a proof of permanent residence in the United States. Your nationality is still China, so your ID card is valid.

The requirement of changing nationality means that you can apply for American citizenship 90 days in advance after getting a green card for 5 years. Requirements are: lived in the United States for more than two and a half years in the last five years, and lived in the United States for more than half a year in the last year. After submitting the application form, you need to check it. You can get American citizenship under oath.