I am going to stay at JW Marriott Beijing Hotel, please advise the closest bus line from PEK?

You are advised to take airport express to get to Dongzhimen Station first. It takes around half an hour. And the ticket fare is CNY 25 per person. Then transfer to metro line 2 to Xuanwumen Station, Exit G. It takes around 20 mins. And the fare is CNY 4 per person. After arriving, walk south along Xuanwumen Outer Street around 700 yards to find the hotel.