Hi,there is one There is one shuttle bus everyday operated by Air Asia for their passengers, between Shanghai Huangpu Bus Station and Hangzhou Airport. In the event of flight schedule change, this bus service will depart 1 hour after the arrival of AirAsia X flight. If you take the Air Asia flight, you can catch it.
If not, you may miss the departs time of it at such late time.
Thus, it is better for you to to get to Hangzhou Train Station first by taxi or airport shuttle bus. Then take bullet train to Shanghai.