Abstract: A method of GC-MS for the determination of 10 semi-volatile organic compounds, including nitrobenzene, trichlorobenzene, nitrochlorobenzene, tetrachlorobenzene, hexachlorobenzene and etc in water with separation by purging and trapping was proposed. The temperature and time for purging were set at 60 ℃ and 8 min, respectively. DB-5MS capillary column was used for GC separation and full-scanning mode was adopted in MS determination with internal standard method for quantification. Linearity ranges for the 10 semi-volatile organic compounds were found in the same range of 0.5-20 μg·L-1 with detection limits (3S/N) in the range of 0.005 9-0.073 μg·L-1. Using surface water, domestic sewage and industrial waste water as matrixes, test for recovery was made by standard addition method, giving values of recovery for the 10 semi-volatile organic compounds in the range of 80.4%-105%, with RSD′s (n=6) in the range of 2.4%-16%.