My friend's green card didn't arrive,but he'll go back to china next Monday,
is there anyone having same problem?
-No.
he already passed the interview and got the I797 approval letter.
with the approval letter, can he enter the costom in USA?
-No. Two choices: 1. Bring the I-485 approval notice and the passport to the USCIS local office to see whether he can get the green card stamp on his passport. If yes, he can use the green card stamp to travel. If no, 2. He can ask someone to send the green card to him and he can use the green card to come back.