I will be going to suzhou from shanghai. What line i take? Help please. Thanks.

Well, subway line 11 will connect to Suzhou in the near future.
But nowadays, you are suggested to take high-speed train from South Railway Station and Main Railway Station, get to Suzhou directly. There are many schedules every day. The trip takes around half an hour. The ticket fare of second class seat is CNY34.5 and first class seat is CNY64.5.