A new method of solvent demulsification dispersive liquid-liquid microextraction (SD-DLLME) was developed for the determination of methyl parathion in the water samples by high performance liquid chromatography (HPLC).In the extraction procedure,a mixture of extraction solvent (trichloroethylene) and dispersive solvent (methanol) was injected into the aqueous sample solution to form an emulsion.In contrast with the conventional DLLME methods,which usually obtained the phase separation through centrifugation,a demulsification solvent (acetonitrile) was injected into the sample tube to break up the emulsion.The dispersed system turned clear quickly.The subnatant (trichloroethylene) was collected and analyzed by HPLC.No centrifugation was required in this procedure.Factors affecting the extraction efficiency such as the type and volume of dispersive solvent,extraction solvent and de-emulsifier were investigated in detail.Under the optimized conditions,the proposed method provided a good linearity in the range of 1-40 ng/mL ( R2=0.999 8).The detection limit ( S/N =3) was 0.03 ng/mL.The relative standard deviations (RSDs) for the determination of 10 ng/mL methyl parathion was 3.3% ( n=5).The proposed method is fast,efficient,convenient and can be successfully applied to the extraction of methyl parathion in natural water samples.