The Frenchman also says his team could still bring in another player before the close of the transfer window after the club saw another key man depart
The midfielder follows captain Robin van Persie out of the Emirates with the Cameroon international due to have a medical in Spain on Monday.
Speaking after Arsenal’s 0-0 draw with Sunderland in their opening Premier League fixture, Wenger highlighted the influence the Gunners had on Song and also hinted that his team could make further signings before the close of the transfer window.
"Yes, he’s going to Barcelona," he told Sky Sports.
"He’s another good player that leaves us and there are two things you feel, always that you did your job, that we take these boys at 17 years of age and we’ve influenced their career in a positive way.
"The second is at their peak, you sometimes lose them, but we’ve got plenty of midfielders and we still might bring somebody in.
"Overall I hope we can compensate that, because we’ve seen what we have faced today. We need quality passing out from midfield and therefore that’s a very important part of the game."
Arsenal have been heavily linked with a loan move for Real Madrid midfielder Nuri Sahin, with Liverpool also reportedly interested in the Turkey international.