OBJECTIVE:To establish a method for simultaneous determination of gallic acid,protocatechuic acid,catechuic acid,corilagin and brevifolincarboxylic acid in Geranium carolinianum. METHODS:HPLC was performed on the column of Won-daSil C18 WR with mobile phase of acetonitrile-0.1% Phosphoric acid(gradient elution)at a flow rate of 1.0 ml/min,the detection wavelength was 280 nm,the column temperature was 40 ℃,and the volume injection was 20 μl. RESULTS:The linear range was 0.02-20.02 for gallic acid(r=0.999 9),0.01-20.10 for protocatechuic acid(r=0.999 7),0.02-19.78 for catechuic acid(r=0.999 6), 0.02-20.02 for corilagin(r=0.999 9)and 0.02-20.10 for brevifolincarboxylic acid(r=0.999 5);RSDs of precision,stability and re-producibility tests were lower than <3.0%;recoveries were 95.1%-100.6%(RSD=2.20%,n=6),95.8%-100.6%(RSD=1.74%,n=6),95.1%-101.9%(RSD=2.71%,n=6),97.7%-103.1%(RSD=2.04%,n=6)and 95.3%-99.0%(RSD=1.46%,n=6). CONCLUSIONS:The method is simple,accurate and reproducible,and can be used for the contents determination of gallic ac-id,protocatechuic acid,catechuic acid,corilagin and brevifolincarboxylic acid in G. carolinianum.