Octenylsuccinic anhydride starch (OSAS) has high viscosity and low solubility in water, which often leads to low efficiency in the esterification reaction between starch and octenylsuccinic anhydride under alkaline conditions, and uneven distribution of octenylsuccinic anhydride (OSA) groups. Enzymatic hydrolysis of OSAS can solve this problem. Using waxy corn starch to prepare OSAS, the molecular weight of enzyme-modified octenylsuccinic anhydride starch (E-OSAS) decreased with the addition of pullulanase. The degree of substitution of E-OSAS was greater than that of OSAS, and as the amount of pullulanase increased, the degree of substitution of E-OSAS showed an upward trend, while the apparent viscosity decreased significantly. The smaller particle size and polydispersity index (PDI), the larger the absolute value of the zeta potential. E40-OSAS, with the smallest particle size, the best homogeneity and stability, had the smallest weight average molecular weight (1.38×106 g/mol), the smallest number average molecular weight (1.37×105 g/mol), and the largest degree of substitution of 0.019. This study provides some basis for the research of new microcapsules.