reply

中国人（没有绿卡）在美国出生的小孩，怎么保持美国国籍，
-The child US citizenship is permanent, and not need to do anything.

怎么回中国在中国生活，然后怎么回美国？
-Because the parents are Chinese citizens who have no green card when the child was born, the child needs to apply for "旅行证" in the Chinese Embassy/Consulate in US to travel to China. Check the Chinese Consulate website which covers your state for details.

谢谢