We proposed a method of determination for benzoic acid,salicylic acid and Pseu-dolaricis, in tincturae cortex Pseudolaricis Co.Benzoic acid was measured at 220～ 230nm ,at 2nmintervals,using 6-point quadratic orthogonal polynomial to calculate P_2. Linear regression was ob-tained for the content vs P_2 value,r=0. 9986. Salicylic acid was measured by l-order derivativespectrum,at 265～330nm. linear regession was obtaied for the content vs valley depth,r=0. 9995.The content of pseudolaricis was measured by the absorbance at 360nm.Its concentration was proportional to absorbance,with r=0.9982 for the linear regression.The mean recoveries(±RSD) of the three ingredients were 99.25%±1.22%,99.39%±0.44%,99.25%±1.00%,respectively.