Abstract: GC-MS/MS was applied to the determination of residual amounts of 37 kinds of pesticides in horseradish. The sample was extracted with a mixture of ethyl acetate and acetonitrile (15+85), and the extract was purified with PSA, activated carbon and anhydrous sodium sulfate. After speedy centrifugation, the supernatant was concentrated and made up to 1.0 mL with methylbenzene. VF-5MS column was used for separation, and MS/MS was used for determination with internal standard method for quantification. Values of lower limits of determination (10S/N) found were in the range of 0.005-0.1 mg·kg-1. Tests for recovery were made by addition of pesticide standards at 4 different concentration levels to blank sample of horseradish as matrixes, values of recovery found were in the range of 61.1%-120%, with values of RSD′s (n=7) in the range of 2.9% to 19%.