I want to go from shanghai pudong airport by metro to a tianchang bus station and after go by bus to tianchang city

Do you refer to the Tianchang city in Anhui province? If so, take subway line 2 to People's Square, where transfer to line 1 to SH General Long-distance Bus Station. Two buses are scheduled to Tianchang at the bus station, leaving at 07:15 and 13:10 and the bus fare is CNY98 per person.