A new symmetrical 1,3-dihexylimidazolium bis［（trifluoromethyl）sulfonyl］imide（［HHIM］［Tf2N］） was synthesized and characterized,and was for the first time employed as extraction solvent in dispersive liquid-liquid microextraction（DLLME） for enrichment and determination of four polycyclic aromatic hydrocarbons（PAHs） including chloronaphthalene,fluorene,anthracene and chrysene in environmental water sample by high-performance liquid chromatography（HPLC）.The extraction conditions influencing extraction efficiency,such as kind of extraction and disperser solvent,volume of extraction and disperser solvent,salt concentration,extraction and centrifugal time were investigated in detailed.Under the optimal conditions,the proposed method provided good linearities for all analytes with correlation coefficients（r2） of 0.999 0- 0.999 8.The relative standard deviations（RSDs,n=5） for four analytes varied between 1.5% and 5.0%.The limits of detection for the method（S/N=3） ranged from 0.002 5 μg?L-1 to 1.0 μg?L-1 and the enrichment factors were in the range of 183-372.This developed method was convenient,speedy,highly sensitive,environment friendly,and was successfully applied in the detection of 4 real water samples（e.g.tap water,ground water,rain water and river water） with recoveries of 84.7%-115.2% and RSDs of 1.6%-6.4%.