Abstract: The effects of different carbons and nitrogens on characteristics of starch degrading enzyme from Aspergillus niger in solid state fermentation were studied. And synthenic regularities of glucoamylase, acidic α-amylase and isoamylase were also explored. Orthogonal experiment was used to optimize medium compositions further, and its results showed that the optimial medium components for isoamylase were composed of bran 7.5g, glucose 0.06 g, amylopectin 0.24 g, yeast powder 0.5g and nutritive salt solution 8m L based on analysis of variance (ANOVA) and S-N-K method with SPSS software. Under the above medium, formation time of highest isoamylase activity was shorten, while the highest activity of glucoamylase and acidα-amylase were decreased by 36.7% and 166%, respectively. It was benefit for further isolation and purification of isoamlyase.