How long does it take by the subway to go from Beijing airport to west railway station ? Thank you !

If by metro, you need to transfer a few times. Upon landing, take airport express to Dongzhimen first. The duration is about half an hour. It costs CNY 25 per person. Then take metro line 2 to Xizhimen and line 4 to National Library. After that, take line 9 to the West Railway Station. It takes around 35 mins. The ticket fare is CNY 5 per person.