Abstract: Objective: To purify GST-granulysin fusion protein expressed in E.coli and identify its antibacterial activity in vitro.Methods: E.coli was sonicated after it was induced by IPTG,and GST-granulysin fusion protein was separated from the soluble extract.The fusion protein was purified by affinity chromatography with glutathione agarose.Its bactericidal activity was analysed by MTT assay.Results: Expression of GST-granulysin in E.coli was detected by SDS-page methods.After affinity chromatography,a single protein band at about molecular weight 44 kDa was obtained.The result of bactericidal activity analysis indicated that it showed potent antibacterial activity against Staphylococcus aureus and Streptococcus sanguis,but it showed weaker antibacterial activity against Salmonella enterica and E.coli BL21.Conclusions: The GST-granulysin fusion protein was successfully purified,and it exhibits effective bactericidal activity against gram positive bacteria.