In this paper,differences of enzymolysis characters among A-type microcrystal starch and native maize starch and acid-hydrolyzed maize starch were studied.A-type microcrystal starch was prepared by recrystallizing short straight chains from water-solution,and under a certain condition,all starch substrates before and after heating were subjected to enzymatic degradation by α-amylase,and compared the extent of enzymolysis.Before heating,A-type microcrystal starch is more available to α-amylase than native maize starch and acid-hydrolyzed maize starch,and native maize starch is much more hydrolyzed than acid-hydrolyzed maize starch but enzymolysis rate of acid-hydrolyzed starch is faster,after heating,the final rate of enzymolysis of all starch substrates was improved quickly.These showed that enzymolysis characters of A-type microcrystal starch are related with morphology,inner structure;more over,length of chains and crystal defects have some influen ces on it.