Crystalline structures and morphology of four different cornstarches with different amylose/amylopectin content were investigated.The vitro digestibility of four cornstarches was tested according to Englyst method.The re-lationship between starch structure and digestion mechanism was discussed.High-amylopectin(waxy and normal) and high-amylose(Hylon Ⅴ and Hylon Ⅶ) cornstarches belong to A-and B-type structures,respectively.A-type starches are"inside-out"digestion mechanism,while the B-type starches produce a different hydrolysis pattern ob-served as"exo-pitting".The level of slow digestion in high amylopectin cornstarch was higher than high-amylose cornstarch,while the Resistant Starch(RS) content of high-amylose cornstarches is much higher than high amylopec-tion conrstarch.