Barcelona is only 150km from the French border. This makes visiting France from Barcelona (or vice versa) very easy to do.
On this page you will find out about how to get from Barcelona to various cities in France. A lot of the routes here are only by bus. If you want to travel by train, see Train Routes from France to Spain.
When traveling from Barcelona to France, you will almost certainly go past Figueres, home to the Salvador Dali museum. It is well worth a visit. Read more: Salvador Dali Museum in Figueres.