You could take NJU campus shuttle bus to come and back between Gulou and Xianlin campus. Please use your campus card to pay for the fee of shuttle bus. Each time would cost 4 yuan RMB.
The document at the bottom is the NJU Campus Shuttle Bus for Weekdays Timetable. Please download it if you need.
Campus shuttle bus get-on station (In Gulou)
Campus shuttle bus get-on station In Xianlin, near International College
Campus shuttle bus get-on station In Xianlin, near School of Government
On Xianlin campus, you can take the On-Campus Shuttle Bus with your Campus Card to pay the fare, which is cost 0.5 yuan each time for student and 1 yuan for faculty. If you pay it in cash, it is 1 yuan.
Since Xianlin campus is very large, it is much more convenient to ride a bicycle to go around the campus. You’d better buy or rent a bicycle.