I want to ask marriage immigration about going to the United States at 30.

Since you call him "America", you must have a bad opinion of him. Thinking about getting married is just for identity.

Instead of thinking about pensions, you should actually think about how to survive in America.

After many people marry Americans for the purpose of identity, domestic violence, lack of financial resources and other problems are manifested after marriage.

Besides being alert to this risk, you should also think about whether you can find a job after coming to the United States. Domestic academic qualifications are not recognized by the United States. English is not good, and it is useless to be strong. Even if you are a postdoctoral fellow in China, you can only start from scratch in the United States.

After you are naturalized, as long as you are not found to be an American citizen, your pension will be fine, and if you are found out, it will be gone.

As for American pension, it depends on your working years and working level.