Abstract: Isotope dilution-high resolution gas chromatography-high resolution mass spectrometry (ID-HRGC-HRMS) was applied to the determination of 27 organochlorine pesticides (OCPs) in soil and sediment.The sample was extracted with a mixture of dichloromethane and acetone (1+1) in accelerated solvent extractor.The extract was purified by a gel permeation chromatographic column and a mixed column containing silica gel and alumina as stationary phase,and then separated on a DB-5MS non-polar column.The OCPs were analyzed qualitatively and quantitatively by the method of isotope dilution.The detection limits (3s) of this method for all 27 OCPs were within 0.11 μg·L-1.The recovery rates measured by standard addition method ranged from 65.1% to 102% and RSD (n=5) were less than 7.0%.