Abstract: Gas chromatography with electron capture detector was applied to simultaneous determination of 22 organochlorine pesticides (OCP′s) in water.OCP′s was separated and enriched from the water sample by extraction with n-hexane.The extract was concentrated and diluted to 1.0 mL with n-hexane.The double capillary chromatographic column practice,i.e.use of 2 columns of different polarity (the Rtx-CLP Ⅱ column and the Rtx-1701 column) was adopted for identification of the OCP′s by comparing values of tR with reference materials,and quantification of the OCP′s was performed by using the Rtx-CLP Ⅱ column with external standard method.Linear relationships between values of peak area and mass concentration of the 22 OCP′s were found same in the range of 1-80 μg·L-1,with detection limits (3s/k) in the range of 1.5-5.6 μg·L-1.Recovery of the method was tested,giving values of average recovery ranged from 73.3% to 107.9% and RSD′s (n=7) ranged from 2.9% to 14.8%.