A high-performance liquid chromatography-tandem mass spectrometric（HPLC-MS/MS） method was developed to analyze abamectin in sediment.The sample was extracted with a mixture of hexane and acetone by ultrasound-assisted microwave extraction,and purified with solid phase extraction column packed with primary/secondary amine and graphite carbon black.The analytes were separated on a Thermo-C18 column（50 mm×2.1 mm,1.9 μm） using a mixture of acetonitrile∶acetic acid-ammonium acetate∶water（75∶10∶15） as mobile phase.The analysis of the target compounds was performed under atmospheric pressure chemical ionization mode with multiple reaction monitoring.The quantification of abamectin was based on internal standard calibration（emamectin benzoate as the internal standard）,and the calibration standards were prepared using matrix matched solution for compensation of matrix effect.The calibration curve of abamectin was linear in the range of 1.6-400 μg/L with correlation coefficient（r2） of 0.999 3.The relative standard deviations ranged from 2.2% to 16.2%,and the limit of detection was 0.18 ng/g by dry weight.The established method was used to analyze sediment samples collected from an urban stream in Guangzhou,and the results were compared with those obtained by the HPLC/fluorescence detection after derivatization.Similar results were achieved by both methods,but the HPLC-MS/MS method showed greater sensitivity and simplicity,and was suitable for the detection of sediment-associated abamectin at low concentrations.