Acarbose，a potent a-glucosidase inhibitor，is one of the most popular drugs for the treatment of non-insulin-dependent diabetes.Currently most investigations focus on increasing the acarbose titer and decreasing the production of byproduct.The effect of aminocyclitol compound validamycin on the fermentation process of acarbose was investigated.It was deduced that validamycin not only enhanced the consumption of carbohydrate，the growth of cell and the accumulation of acarbose，but also inhibited the generation of byproduct component C.A fed-batch fermentation strategy that added an appropriate amount of nitrogen and carbon source in 72 h and 96 h after inoculation was adopted with the addition of 0.08 g·L-1 validamycin A into the medium.As a result，the maximum acarbose titer reached 5602 mg·L-1，increasing by 57% compared with the control，and the byproduct component C decreased by 54% simultaneously.