Four protease-producing Mucor strains were isolated from sixteen type strains preserved in our lab,which were 3.4906,3.4909,3.4943 and 3.5009 respectively.We found that plate screening was not easy to observe in Mucor screening and should be improved.Fermentation and detecting the protease activity is the most direct and effective screening method.The protease in the fermented liquid of these four isolated strains was researched.The results showed that proteases which produce by the strains of 3.4943 and 3.4906 had good temperature stability;optimum reaction temperature of proteases which produce by the strains of 3.4906 and 3.5009 is lower than that of3.4943 and 3.4909;In terms of reaction p H,the optimum p H of 4 kinds of proteases produced from 4 strains was in the range of 6.0 ~ 8.0;In affected by the concentration of Na Cl,protease activity of 3.4943 was greatly influenced by Na Cl concentration and that of 3.4909 was least affected by the concentration of Na Cl.Because each strain of enzymatic characteristics varies,we could select suitable strains in production of fermentation food.