Abstract: Accelerated solvent extraction and on line purification of hexachlorocyclopentadiene, hexachlorobutadiene and hexachloroethane in soil for GC-MS detection were studied in this research. Soil sample (10 g), mixed with silica sand (20 g), was placed in the extract cell with fluorine silica powder (1 g) and graphitized carbon powder (0.2 g); and then the polychlorinated hydrocarbons were eluted by mixture of dichloromethane and acetone (4+1). Influence of temperature, extracting solvent, dispersing agent, pH and TOC content were studied. Difference of on line and off line purification as well as superiority of composite purification were also analyzed in this study. The proposed method was applied to the analysis of 3 different soil samples, giving values of recovery and RSD′s in the range of 72.3%-89.0% and 7.4%-13% respectively.