I immigrated to US 15 years ago from China and now want to moving back to China permanently.

In general, getting a permanent resident is hard in China. People who want to get a permanent resident card need to live in China for consecutive years or get married with a Chinese guy or make contribution to Chinese society or unmarried person living with their parents in China. Then he/she has is able to apply a resident permit, but whether he/she can get depends on the government.

You can choose to apply for a S1 to live with your father in China first and then seek for for methods or solutions. Or you can consult the local Chinese embassy/consulate and maybe they have better methods.