You can visit wineries in Catalonia via bus or car. Busses and coaches connect the main cities in Catalonia with many national and international destinations. Bus stations in Barcelona are: Estació de Sants and The Estació del Nord.
In every bus station, train station or airport, you can rent a car to better get to wineries in Catalonia. Normally, it takes 1.5h or 2h to reach the majority of wineries in Catalonia from Barcelona, as most of them are in the countryside. Don’t forget to visit wineries in Priorat, where some of the most classic Cava in all of Spain is produced.
If you travel to wineries in Catalonia by car, just follow indications to Barcelona, the absolute heart of Catalonia.