What is the procedure for my American husband to immigrate to China?

China is a non-immigrant country, so it is difficult to immigrate to China unless it makes a significant contribution to China.

However, your husband can apply for a Q/KLOC-0 visa, and then apply for a residence permit at the entry-exit administration office where you live. You can live for a long time and renew it after it expires. To apply for a residence permit, you need to make an appointment in advance to the designated physical examination institution for physical examination and get the physical examination report.