Pay in China 15 years, and immigrate to the United States before retirement age. What about social security?

You can surrender your insurance or keep it.

It is generally recommended to keep it because I don't know if I will return to China or even restore my nationality in the future.

Moreover, some experts have said that even if you are a person of another nationality, as long as you have paid the social security for the relevant years, you can get a pension when you reach the old age limit.

Of course, the specific choice still depends on personal wishes.