18.4 km. According to Baidu map, the whole journey from Xiamen Gao Qi Airport to Xiamen University is18.4km, and it takes 42 minutes by car. The driving distance is as follows:

1. First, drive from Xiamen Gao Qi Airport to National Highway 304.

2. Next, drive north along National Highway 304 to National Highway 309.

3. Finally, go straight along University Road for 6.3 kilometers to reach Xiamen University.