Abstract: A dispersive microextraction solution composed of 20.0 μL of tetrachloroethylene and 1.0 mL of acetone was added into the water sample (5.0 mL) which was added NaCl (100 mg). GC-MS was applied to the determination of heptachlor epoxide in the extract phase. The DB-5ms quartz capillary chromatographic column was used for GC separation and the selected ion monitoring mode was adopted in MS determination. Linear relationship between values of peak area and mass concentration of heptachlor epoxide was kept in the range of 0.5-200 μg·L^-1, with detection limit (3S/N) of 0.1 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 81.6%-97.4%, with RSDs (n=5) of determined values in the range of 4.6%-7.2%.