When you enter US, you need to tell the IO at the port of entry that you have known your I-485 has been approved during your travel in China. Of course, you have to have the valid H-1 visa stamp on your passport to leave US. If you don't have H-1 visa stamp, you have to use the green card to enter US (you can not apply for the H-1 visa stamp due to I-485 approval).