From Beijing Capital International Airport (Terminal 1~3) to Xijiao Hotel:
1. Taxi: the cost is around 100 - 150 CNY. If you arrive after 23:00, a taxi ride is the only choice.
2. Subway (06:20-22:50, 30 CNY): Take Airport Line (Subway), transfer at Sanyuanqiao Statio to Line 10. Then transfer at Zhichunlu Station to Line 13. The destination is Wudaokou Station, which is a 15-minute walk to the Xijiao Hotel.
3. Airport Shuttle Bus (06:50- 01:00 the next day, 30 CNY): Shuttle Line 5 to Zhongguancun will take you to the Southeast Gate of Tsinghua University Campus. Then you have to walk to the Xijiao Hotel (20-minute walk).
More information and walking directions are provided here (pdf file).