A high performance liquid chromatography method for the determination of pydiflumetofen residues in watermelon was developed using dispersive solid phase extraction and dispersive liquid-liquid microextraction as sample preparation methods.The samples were extracted with acetonitrile and water solution,purified with primary secondary amine as sorbents,and concentrated into 1,1,2,2-tetrachloroethane by dispersive liquid-liquid microextraction.The extracts were analyzed by high performance liquid chromatography.The conditions affecting the purification efficiency of the dispersed solid phase extraction,including the extraction solvent and the type of adsorbent were optimized.Factors affecting the extraction efficiency such as type and volume of extraction solvent,volume of dispersive solvent and salt concentration,were investigated.The results indicated that the calibration curves for the analytes were linear in the concentration range of 0.01-5 mg/L with the correlation coefficients of 0.999 9.The limits of quantification(S/N=10)were 0.01 mg/kg.The mean recoveries at three concentration levels of 0.01,0.1,1 mg/kg were in the range of 89.2%-94.5%with the relative standard deviations below 8.7%.With the advantages of simplicity,high efficiency and sensitivity,the proposed method was applicable for the analysis of pydiflumetofen residues in watermelon samples.