Hongkong to Hangzhou

First, you don't need a visa to visit Hong Kong. However, a valid China visa should be prepared before you depart to Hong Kong. It is suggested that you get the visa in advance in your country.

Since the long-distance, it is suggested that you fly to Hangzhou directly. There is no train or bus running between these two city at present. For instead, you could take a train (19 hours) from Hong Kong to Shanghai and then transfer to Hangzhou by train in 2 hours.