According to Baidu map query, you can take the subway 13 line from Huilongguan to Beijing West Subway Station, and then transfer to Line 4 and Line 9. The whole journey is 6 1 min, ***27.4 km.

Mode of transportation: Take the subway 13 line (Xizhimen direction) from Huilongguan to Xizhimen Station, pass 8 stops, then transfer to Metro Line 4 (Anheqiao north direction), pass 2 stops, arrive at National Library Station, get off and transfer to Metro Line 9 (Guogongzhuang direction), and pass 4 stops to Beijing West.