The train is a fast and economic choice to get to and from the Barcelona Airport.
Barcelona airport has a direct train connection to the city center. The train is an excellent choice, especially for the budget travelers. If you buy a T-10 (10 ride ticket) for the zone 1, you can ride to the center of Barcelona without an extra charge, so it is even cheaper than the Barcelona Metro.
The airport train station is located just in front the terminal one (T1). It takes about 20 minutes ride to the center and the trains leave every 30 minutes between 6.00 A.M. and 11.00 P.M.
If you are coming to the airport, you can catch the train in Clot, Passeig de Gracia, or Barcelona Sants train stations.