Suzhou is most easily reached from Shanghai by high-speed train. The journey from Shanghai Hongqiao station takes around 30 minutes on the G-line trains; from Shanghai's main station it takes around 40 minutes. Trains run frequently throughout the day and tickets are inexpensive. The station receiving these services is Suzhou Station, centrally located and well connected by metro.
A slower option — and in many ways a more interesting one — is the older D-line train from Shanghai, which stops at more stations and takes around an hour. Trains from Nanjing take 30-40 minutes on the high-speed line. Direct trains from Beijing take around 5 hours.
There is no airport in Suzhou itself. The nearest airports are Shanghai Pudong and Shanghai Hongqiao, both of which have good onward train connections. Some travellers also use Wuxi Sunan Shuofang Airport, which is closer but has limited flight options.