How to renew the American visa after one year?

Six months. At present, American tourist visas can be applied for 3 months, 1 year, 3 years, 5 years and 10 year, but generally they can stay for up to 6 months (180 days) each time. The specific stay time is determined by the customs. When entering the country, the date of departure should be stamped on the passport, which usually takes 1-3 months. The stay time of the tourist visa to the United States is about to expire, but if you want to postpone going abroad for a while, you can apply to the US Immigration Service for an extension. You should note that it is uncertain whether the application is approved, and the application should be submitted before the tourist visa expires.

Legal objectivity:

People's Republic of China (PRC) Exit and Entry Administration Law

Article 9

China citizens shall apply for passports or other travel documents when leaving or entering the country.

China citizens who want to go to other countries or regions also need to obtain visas or other entry permits. However, unless the China government has signed visa exemption agreements with other governments or the Ministry of Public Security and the Ministry of Foreign Affairs provide otherwise.

China citizens who leave or enter the country as seafarers and work on foreign ships shall apply for a seaman's certificate according to law.