Abstract: GC-MS/MS was applied to the determination of residual amounts of 7 pyrethroid pesticides (i.e., bifenthrin, fenpropathrin, cyhalothrin, permethrin, cypermethrin, fenvalerate and deltamethrin) in tilapia. The sample was extracted with a mixture of cyclohexane-ethyl acetate (1+1) by accelerated solvent extraction, and the extract was purified on Florisil solid phase extraction (SPE) column. The 7 pyrethroid pesticides were eluted from the SPE column with a mixture of acetone-n-hexane (1+9) and the eluate was evaporated to near dryness by N2-blowing on a water bath at 45 ℃. The residue obtained was dissolved and made up to 1.0 mL with n-hexane, which was used for GC-MS/MS analysis. TR-5MS capillary chromatographic column was used for separation, and the selected reaction monitoring (SRM) with electron impact ionization source was adopted in MS. Values of detection limit of 7 pyrethroid pesticides were found in the range of 0.20-2.1 μg·kg-1. On the base of blank sample of tilapia, test for recovery was made by standard addition method, values of recovery found were in the range of 57.9%-107%, with RSD′s (n=6) less than 12.0%.