I would like to know the route number for the bus to go from Harbin Institute of technology to the Harbin Airport

To catch an early plane, you can walk from the university to Jiaohua Square bus stop to catch bus no. 348 or 22 to Anhuaqiao Station. Upon your arrival there, transfer to shuttle bus line 1 to the airport directly. The first bus of shuttle line 1 leaves around 06;00. If it is not early enough, you'd better catch a taxi to reach. As I know, the hotel near the airport is expensive.

How long will the bus take to go to the airport? my flight is at 7.50

Will there be cheap hotels arrange shuttle service to Airport?

I just got to know that the shuttle bus can take you from the university to the airport directly. However, the first bus leaves around 06:00 and the whole journey takes around an hour. Time will not be enough to catch your plane. Therefore, I suggest you take a taxi to catch up. The taxi fare shall be around CNY130.

Generally, cheap hotels don't arrange shuttle bus service in the city.