Beijing has several beer festivals but only a couple are really worth the trip. This year, the most promising beer festival seems to be the Oktoberfest (a.k.a. Beijing International Beer Festival) which takes place on Crab Island until August 15th. See the link below for more info. Another popular one among locals is the Yanjing Beer Festival but that's already passed.

Last year, I happened to stumble upon the beer festival held at Solana, and let me tell you, it was the most depressing excuse of a beer festival I've ever seen. Just imagine a stage with a mediocre band, a mediocre sound system, and about 10 disinterested people not drinking beer or listening to music, but taking advantage of the benches to rest in between shopping - that's what the Solana beer festival was like!