Abstract: A rapid method for the determination of dufulin residues in the carp and crayfish by QuEChERS-high performance liquid chromatography-tandem mass spectrometry was developed. The samples were extracted with acetonitrile, and cleaned up by 50 mg PSA, 50 mg C₁₈ and 50 mg MgSO₄. The samples were separated on a Eclipse XDB-C₁₈ column, and detected under positive polarity multiple reactions monitoring (MRM) mode. The matrix matched external standard calibration curves were used for quantitative analysis. The result indicated that the good linearities of dufulin was in the concentration range of 1.0-50 μg/L with correlation coefficients higher than 0.999. At the fortified levels of 10, 50 and 100 μg/kg, the average recoveries of dufulin in the carp and crayfish, were in the range of 88%-103%, with intra- and inter-day relative standard deviations varies from 1.2% to 5.4%. The limit of detections(LOD) for carp and crayfish were 0.4 and 0.8 μg/kg, respectively. And the limit of quantifications(LOQ) of dufulin for them were 2 and 3 μg/kg, respectively. This method was simple, accurate, economic and friendly to the environment, which could meet the requirements for rapid determination of dufulin residues in the carp and crayfish.