Abstract: The water sample was filtered through a 0.22 μm hydrophilic syringe filter, diluted as needed, and separated on an Acclaim Mixed-Mode WAX-1 column (4.6 mm×150 mm, 5 μm), with 90 mmol·L^-1 phosphate buffer solution ［pH 6.0, 10% (volume fraction) acetonitrile solution as solvent］ as mobile phase for elution. UV detection was performed at the wavelength of 210 nm. The results showed that linear relationships were obtained between peak area and mass concentration of glycolic acid, glyoxylic acid and oxalic acid in the ranges of 3.51-2 500, 4.20-8 000 and 18.0-800 mg·L^-1, respectively. The detection limits (3S/N) were 1.00, 1.24, 4.82 mg·L^-1, and the lower limits of determination (10S/N) were 3.32, 4.15, 16.1 mg·L^-1. Tests for recovery was made by standrard addition method to the actual samples, giving values of recovery of glycolic acid, glyoxylic acid and oxalic acid between 98.2%-101%, 99.6%-103% and 99.2%-101%, respectively. The relative standard deviation of the measured values (n=6) were 0.77%, 0.65% and 1.1%, respectively.