The best way is to take the bullet trains. There are more than 30 bullet trains (also known as D trains) between Shanghai and Hangzhou, which will only take about 1.5 hours. So, you can take a D train in Shanghai South Railway Station or Shanghai Railway Station but there are only 5 D trains in Shanghai Railway Station. Besides, Hangzhou also has two railway stations, Hangzhou and Hangzhou South, the later is far from downtown Hangzhou. Thus you need to pay more attention to your departure and arrival stations. Also, there are more than 30 D trains between Hangzhou and Shanghai. To have a one-day tour to Hangzhou, you need to take an early train in Shanghai and you can return from Hangzhou in the evening. The latest D train from Hangzhou (not Hangzhou South) to Shanghai South is D3106, departure time: 21:15.

To go to Shanghai Railway Station or Shanghai South from Nanjing Road E, you can take the Subway Line 1 at People’s Square but be aware that the two railway stations are in opposite directions.

Thank you very much. It is very detailed and informative.
Thanks again.