Abstract: An ultra high performance liquid chromatography(UPLC) method with mixed organic solvent extraction for simultaneously determining the phenylglyoxylic acid(PGA) and mandelic acid(MA) in urine samples was established,fifty urine samples of smokers and non-smokers were detected by the established method.The results showed that:1) The extracted urine samples could be introduced directly after dilution with mobile phase,it only took 8 minutes to complete a UPLC analysis.2) The concentration suitable for working curve of PGA and MA ranged from 0.425 to 21.500 μg/mL and from 1 to 100 μg/mL,respectively;the correlation coefficients were above 0.9995.3) The quantification limits and recoveries of PGA and MA were 0.013 and 0.077 μg/mL,86.67%-96.33% and 88.50%-97.17%,respectively;and the intra-day and inter-day precisions were all less than 8% and 10%,respectively.4) The contents of PGA and MA in smokers' urine samples were all higher than those in non-smokers' with significant differences(P<0.05).This method is simple,rapid and accurate for determining the contents of styrene metabolites in urine.