Abstract: GC-MS was applied to the determination of 25 volatile organic compounds in water with headspace sampling.The water sample was extracted for 30 min at 80 ℃ in headspace flask under static condition.HP-VOC chromatographic column was used for GC separation and the full-scanning mode and the selected ion monitoring mode were adopted in MS determination.Linear relationships between values of peak area and mass concentration of the 25 volatile organic compounds were kept in definite ranges.Detection limits found were ranged from 0.13 to 2.06 μg·L-1.On the base of blank sample,test for recovery was made by standard addition method;values of recovery found were in the range of 75.1%-109% with RSD′s (n=6) in the range of 2.2%-9.8%.