A method is described for the screening of semivolatile organic compounds in water samples by GC/MS. The 160 compounds of semivolatiles including pesticides, polycyclic aromatic hydrocarbons, phenols, phthalates, and nitrobenzenes could be separated by GC/MS within 33min. It was possible to distinguish of overlapped counpounds using the extracted ion chromatogram of each compounds drew out by macro program. The sample preparation involved extraction of the basic compounds at pH 11 followed by a second extraction of the acidic one at pH 3. After extraction, it was possible to concentrate by evaporation after adding 60㎕ of triethylamine. The method detection limits ranged from 0.001 to 1.0 ng/㎖.