Abstract: A method for the determination of 15 organophosphorous pesticide residues in water samples by gas chromatography （GC） with largebore capillary column and equipped with flame photometric detector (FPD) was developed. The parameters of the GC determination were optimized and the factors which influence the determination results were discussed. The detection limits of this method for different substances are 0.0077~0.1350 μg/L with precision of 2.2%~9.3%RSD(n=10). The correlation coefficients for all pesticides (except for omethoate) are better than 0.99. This method is suitable for the determination of organophosphorous pesticides in water amples ith the advantages of rapidity, simplicity, high sensitivity and accuracy.