BOBBY BROWN just got his second DUI of the year.  He got picked up yesterday morning at around 1:00 A.M. after cops saw him weaving down an L.A. street.

They pulled him over and gave him a field sobriety test, which he failed.  Cops say he also flunked a breathalyzer test, but we don't know the results.

Bobby also got nailed back in March, about a month after the death of his ex-wife WHITNEY HOUSTON.