Abstract: Both gas chromatography-mass spectrometry(GC/MS) and gas chromatography-electron capture detector(GC-ECD) method were used to determine 9 organic chlorine pesticides in water and soil samples. GC-ECD caused a false-positive interference to determine organic chlorine pesticides while GC/MS got accurate and reliable results which can be an efficient method for organic chlorine pesticides determination in water and soil samples in environment. Experimental data show that using GC/MS can be identification of organic chlorine pesticides in water and soil, and improving the accuracy of analytic result.