Abstract: Three kinds of materials including IPTG, lactose, and mercaptoetanol were used as the inducers to induce the expression of recombinant human manganese superoxide dismutase. The results show that all these materials can induce the expression of exogenous rhMn SOD protein. By assaying the enzyme activity, specific activity and applying electrophoresis, the results show that the induction effect of lactose is better than that of the other two materials. And further experimental result indicate that the optimum concentration of lactose is 80mmol/L.