Abstract: Adetermination of OPs-residue pesticides in vegetables has been developed by gas chromatography-positive chemical ionization mass spectrometry(GC-PCI-MS).Pesticides were extracted from sample with acetonitrile in an ultrasonic bath and cleaned up on GPC,then were determined by gas chromatography with positive chemical ionization mass spectrometric detection in a selected ion monitoring mode.The method was accurate,sensitive and selective,the average recoveries ranged from 69.5% to 121.8%,whilethe relative standard deviations ranged from 1.69% to 11.01%,lowest detectable limit ranged from 0.69 to 4.24μg·kg-1.