The 28-kilometer’s Airport Express of Beijing subway has been put into use on July 19, 
2008. This light rail line running from the T2 and T3 of Capital Airport just has two stations in Beijing’s downtown area, respectively at Dongzhimen and Sanyuanqiao. It just takes 20 minutes for passengers to travel between the airport and Dongzhimen by the Capital Airport Express Train, the highest speed of which could reach 110 kilometers/hour.
Routes
T3 of Capital Airport → T2 of Capital Airport → Sanyuanqiao → Dongzhimen
Dongzhimen→Sanyuanqiao→T3 of Capital Airport→T2 of Capital Airport
Ticket:
Fare: CNY25/person
Ticket of Airport Express Train
At each of the four pick-up stations, you could purchase a card ticket by RMB cash from the manual ticket office or the ticket vending machines which have Chinese and English service. Please keep your ticket well since it will be reclaimed when you exit from the express train station.
Besides purchasing a ticket by cash, the ticket fare could be paid by the Beijing transportation smart card if you already have one. The fare will be deducted from the balance in your card when you exit from the express train station.
How to take the Airport Express Train?
Departure from Capital Airport to Sanyuanqiao & Dongzhimen
When you arrive in Beijing Capital Airport, please follow the signs to the Airport Express Train Station → purchase a ticket and enter into the waiting hall → get off the train and return the ticket → exit from the subway station or purchase another ticket to transfer to subway Line 2, Line 13 or Line 10
Departure from Dongzhimen to Capital Airport
Please enter into the subway station from Exit E on the ground and take the elevator downstairs to B1 → purchasing ticket and go through security check → take the elevator downstairs to B4 → waiting and boarding the Airport Express Train
Tips: If you transfer to the Airport Express Train from subway Line 2 and Line 13 at Dongzhimen, you have to return the ticket which only charges CNY2 firstly. Afterwards, please go to the ticket office of the Airport Express Train to get a new one.