Abstract: GC was applied to the determination of residual amounts of 5 pesticides,i.e.triethyl thiophosphate,atrazine,methyl parathion,parathion and tribufos in water with headspace solid phase microextraction.The optimized conditions found were as follows:① extraction fiber type:polyacrylate;② extraction temperature:80 ℃;③ extraction time:40 min;④ desorption time:5 min.The analytes were separated on DB-35MS column (30 m×0.32 mm,0.25 μm) and detected by NPD.Linear relationships between values of peak area and mass concentration of the 5 pesticides were kept in definite ranges.Detection limits (3S/N) found were ranged from 0.05 to 1.0 μg·L-1.The proposed method was applied to the analysis of samples of reservoir water,giving values of recovery and RSD′s (n=5) in the ranges of 37.0%-107% and 1.6%-25.0% respectively.