Abstract: UHPLC-MS/MS was applied to the determination of residual amounts of 9 organophosphorus pesticides, including pyrazophos, phosalone, ethion, pirimiphos methyl, mevinphos, methidathion, phosmet, diazinon and sulfotep, in aquatic products. The sample was extracted with a mixture of glacial acetic acid-acetonitrile (1+99) and purified by adsorbing agent PSA. The sample solution obtained was separated by UHPLC and analyzed by MS/MS. Linear relationships between values of peak area and mass concentration of the 9 organophosphorus pesticides were found in the same range within 18 μg·L-1, with their detection limits (3S/N) of 0.005 mg·kg-1. Using aquatic products as matrixes, test for recovery was made by standard addition method, giving recovery in the range of 87.5%-102% with RSD′s (n=10) in the range of 3.7%-13%.