An RP-HPLC method was established to separate the related substances of benzyl hydroxybenzoate.The separation was carried out on a Agilent ZORBAX Eclipse Plus Phenyl-Hexyl column.The mobile phase was methonal-0.1％ glacial acetic acid,using linear gradient elution,and the detection wavelength was 254 nm.There was a good linear relationship between 0.051-101.88 μg/mL (r =1.00) and 0.050-99.48 μg/mL(r =0.999 8) for benzyl hydroxybenzoate and p-hydroxybenzoic acid,repectively.The average recovery of p-hydroxybenzoic acid was 100.3％ and the RSD was 0.95％.The LOQ of p-hydroxybenzoic acid was 0.24 ng.The detected impurities were also identified by UPLC-Q-TOF.The established method is accurate and reproducible,and could be used for the quality control of benzyl hydroxybenzoate.