A novel method was developed for the simultaneous determination of three trace phenylurea herbicides,such as isoproturon,metobromuron and monuron in environmental water,by liquid phase microextraction（LPME）coupled with high performance liquid chromatography（HPLC）.The effects of differerent extraction and measuring conditions on detection were investigated.The optimal experimental conditions were as follows:organic solvent:6 mL octanol,drop volume:3 μL,stirring speed:450 r/min,extraction time:30 min.Under the optimal conditions,the enrichment factors of isoproturon,metobromuron and monuron were 510,490 and 350,respectively.There was a good linearity between peak area and concentration of three herbicides in the range of 0.5-800 μg/L,with correlation coefficient of 0.995 8-0.998 3.The detectioin limits of three phenylurea herbicides ranged from 0.2 μg/L to 0.4 μg/L.The spiked recoveries of three herbicides from environmental water samples were in the range of 62%-92% with relative standard deviations（RSDs） no more than 7.7%.The method showed the advantages of sensitivity,simplicity and fastness for the use of very small amounts of organic solvent,and could meet the requirements of the determination of trace phenylurea herbicides in environmental water samples.