am arriving at hangzhou intl airport at pass 12 midnight.

Well, you are suggested to stay at the hotel for that night and start off in the early morning. The bus schedules are 08:40, 09:20, 10:00, 10:40, 11:20, 12:00, 12:40, 13:20, 14:10, 14:40, 15:30, 16:20, 17:10, 18:00, 18:50, 19:40, 20:30, 21:20, 22:10 and 23:00. The ticket fare is CNY62 per person with the duration of around 2 hours.