Aminopeptidase can hydrolyse polypeptide chain to amino acids from N-terminal,so it is applied in the fields of food,industry and medicine.This study optimized fermentation conditions for aminopeptidase production of Bacillus methylotrophilus CC by One-factor experimental design,Orthogonal experimental design and Response surface experimental design.The result showed that the optimal compositions of media were 1% sucrose,1.5% soybean cake meal,0.1% sodium chloride,0.05% potassium d-ihydrogen phosphate and 0.02% magnesium sulfate heptahydrate;the optimal culture conditions were pH value 8.5,temperature 37℃,rotating speed 180r/min,inoculum 6%,culture time 15h.Under above-mentioned conditions,the highest yield of aminopeptidase reached 310.07U/ml and increased by 2.73 times,compared with 83.09U/ml before optimization.