A QuEChERS/HPLC-MS/MS method was developed for the simultaneous determination of imidacloprid,triadimefon,acetochlor and metolachlor residue in corn flour.The residues were extracted from samples with acetonitrile and cleaned up by dispersive method using PSA and GCB，then detected by high liquid chromatography-mass spectrometry(HPLC-MS/MS) under multiple reaction monitoring mode,and quantified by the matrix-matched standard solution.The results showed the method had a good linearity(r2≥0.998) in the range of 0.005-1.000 mg/L.Average recoveries at three spiked levels of 0.05-1.00 mg/kg were in the range of 74.9%-98.4%with relative standard deviations(n=5) of 1.6%-5.3%.The limits of detection(LOD) for 4 pesticides were in the range of 0.001-0.26 μg/kg，and limits of quantitation(LOQ) were in the range of 0.004-0.867 μg/kg.With the advantages of rapidness，simplicity，high sensitivity and good reproducibility,the method is suitable for the determination of target pesticides in corn flour.