A method was established for the quantitative determination of 20 organochlorine pesticides(OCPs) in crayfish by gas chromatography and mass spectrometry(GC-MS)．The preparation and analytical conditions，such as extraction solvent，purification method and other analytical conditions were optimized．The samples were extracted with acetonitrile，and kept in constant volume with ethyl acetate-cyclohexane(1∶1).The extract was purified by gel permeation chromatography(GPC) combined with solid-phase extraction(SPE),and determined by GC-MS under selective ion scan(SIM) mode．Under the optimum conditions，the calibration curves of the compounds were linear in the range of 0.01-1.0 mg/L with correlation coefficients higher than 0.994，and the limits of detection(LOD,S/N=3) were in the range of 0.1-1.5 μg/kg．The recoveries of target compounds in crayfish yellow and meat samples at three spiked concentration levels of 5，10，20 μg/kg were in the range of 71.3%-117.3%，with RSDs(n=6) of 0.6%-7.5%．The method is sensitive，accurate and simple，and could be applied in the determination of 20 OCPs in crayfish. Key words：gas chromatography-mass spectrometry(GC-MS)；crayfish；organochlorine pesticides(OCPs)；gel permeation chromatography(GPC)；solid-phase extraction(SPE)；residue