i am now at bumd hotel near gaungdong road shanghai china.want to go to nantong city at haimen bus stop.

Bund Hotel, right? You can walk from your hotel to Dadongmen bus stop to take bus no. 64 or 930 to SH Railway Station, walk from which to local General Long-distance Bus Station. There you can easily take a bus to Nantong. Upon your arrival, transfer to another bus to Haimen City (is it your destination?).