Abstract: A gas chromatography coupled with negative chemical ionization-mass spectrometric method (GC-NCI/MS) was developed for the determination of fipronil and its metabolites in pond water and shrimp. Target compounds in water were extracted by CH₂Cl₂, cleaned up with a graphitized carbon black (GCB) solid phase extraction(SPE) column. Shrimp sample was extracted by acetone-dichloromethane(3∶4，V/V), the protein in shrimp was moved from shrimp extraction with the 0.1 mol/L pH 7.4 phosphate buffer, the fat in shrimp was removed by liquid-liquid separation with hexane-acetonitrile, then the acetonitrile layer were further cleaned up with a florisil/GCB SPE column．The recoveries of all targets are in the range of 78.7%—115.0%, and the RSDs are in the range of 0.3%—9.9%. Limits of detection of fipronil and metabolites are 0.01 μg/L for water and 0.4 μg/kg for shrimp，respectively, and the linearity of method is good. The sensitivity and selectivity of this method is good enough for the determination trace amount of fipronil and its metabolites in complex matrix samples, and the bioconcentration of factors (BCF) of target components are as high as 1040.