Abstract: Aminopeptidase can hydrolyze polypeptide chain to amino acids from N-terminal,so it is applied in meat processing to increase free amino acids and improve the quality of fermented meat. Utilizing Staphylococcus saprophyticus RG-2 strain isolated from Rugao ham and producing aminopeptidase,we studied the influence of pH,temperature,NaCl on activity of aminopeptidase from the strain RG-2 by the method of single factor experiments and response surface. The results showed that the optimal condition of media was pH6. 8,41℃ and 1% of NaCl. Under above-mentioned conditions,the highest yield of aminopeptidase reached 23. 85U / mg.