Abstract: The optimum conditions of determination of volatile halogenated hydrocarbons in water by purge-and-trap gas chromatography have been studied, by using HP-1 silicon melting capillary column with big-diameter and thick liquid membrane, 10 different volatile halogenated hydrocarbons were trapped by purge-and-trap method and determined by ECD. The standard derivation and coefficient variation were 0.02～0.07 μg/L and 1.09%～3.28% respectively. The recoveries were ranged from 94.0%～107%. The detection limits were 0.07～0.19 μg/L.