China's current population is 1,361,512,576, which is one of the highest populations in the world and this is a big problem there. Overpopulation can possibly lead to starvation, desertification, or species depletion.
Overpopulation in China could affect America by Chinese immigrants moving to America because of lack of space in China. Which could also eventually result in overpopulation in America. America is already one of the most highly populated countries in the world. A solution to stop overpopulation is to not allow immigrants to enter America, so that America doesn't overpopulate
A solution to overpopulation could be moving to new countries. Maybe even spreading over areas that are not inhabited by other humans. Maybe countries could have the One-Child policy that China has.
The following chart is China's past, current, and the predicted future population
The next picture is of the Immigration to the United States of America.