A balance pressure static headspace sampling gas chromatographic method was developed for the determination of HCH and DDT pesticide residues in the transgenic soybean oil using a typical mixed ionic liquids of ［Bmim］PF6-［Bmim］BF4 by a ratio of 1∶2 as a headspace solvent,based on that mixed ionic liquids have the characteristics of low vapor pressure,high boiling point,excellent dissolving ability,good hydrophilicity and hydrophobicity at the same time.Experimantal conditions,including type of ionic liquid,proportion and dosage of ionic liquid,headspace equilibration temperature,headspace equilibration time and headspace sampling time were optimized.The results showed that the calibration curves were linear in the range of 5-100 μg/L,with correlation coefficients of 0.990 5-0.999 6.The detection limits and quantitation limits of 8 pesticides were in the range of 1.4-15.2 μg/kg and 4.7-48.6 μg/kg,respectively.The recoveries and RSDs were 72.3%-104.1% and 0.6%-7.8%,respectively.The method was rapid and accurate,and could be uesed to avoide for the complicated sample pretreatment process.