Abstract: In this paper sample pretreatment techniques including ultrasonic extraction and decontamination techniques of sulfonation and solid phase extraction (SPE) for determination of organochlorine pesticided in soil samples by gas chromatography were presented. The results show that ultrasonic extraction could save the sample treatment time and improve the efficiency of sample analysis. And both of the sulfonation and SPE provide better decontamination effect. But aldrin, dieldrin and endrin in the samples would be lost when sulfonation method was used. Under the optimized condition of acetone/n-hexane=1∶9 and using 8 mL leaching solution in SPE decontamination, the recovery of the analytes was better than 90% and with less interference. Detection limits of the method for organochlorine pesticides were 0.63～2.59 μg/kg and average recovery was 82.78%～106.94% with precision of 1.17%～14.66%RSD (n=7). The method has been successfully applied to the determination of organochlorine pesticides in soil samples in Eco-geochemical Investigation and Assessment Program.