Abstract: In order to study the relationship between Staphylococcal nuclease(SNase)and diabetes mellitus, genetic engineering bacteria E. coli BL21/pET28a-His-SNase was constructed, the expression of soluble extracellular protein SNase was induced and the a preliminary research was made on it. An expression vector pET28a-His-SNase plasmid containing the His-SNase gene was constructed and transformed into E. coli BL21(DE3)competent cells. The protein was induced by lactose and purified by ultrasound destruction and Ni-affinity chromatography, respectively. It was then analyzed by SDS-PAGE and Western blot. The enzymatic properties for SNase has been preliminary studied as well. Results indicated that the purity of the correctly expressed fusion protein His-SNase was over 85%. SNase showed good activity within a wide range of pH and good heat resistance. This experiment might be a foundation work for the further study on the relationship between SNase and with diabetes.