Abstract: Glutathione S-Transferase (GST) is a kind of multifunctional enzyme in organism.In this study,GST was extracted and purified from Earthworm  Eisenia fetida, and the extraction condition was optimized as follows:pH of 7.0,extraction time of 30 s,solid/liquid ratio of 1:8,the saturation degrees for two times ammonium sulfate precipitations were 40% and 80%,respectively.Under these conditions,GST was purified 14-fold;the specific activity of 1.236 U/mg Pr.and the yield of 17.7% were obtained.GST is composed of two subunits,the molecular weight of one subunit is 25 KDa determined by SDS-PAGE,and therefore the molecular weight of GST is 50 KDa.GST was stable in the range of pH 5.0-9.0 and temperature 0-40 ℃.

Key words: earthworm, glutathione S-transferase, flash extraction, purification