The invention belongs to the field of starch modification and application, and discloses a drug excipient prepared through the synergistic effects of chemical modification and enzymolysis on starch. The preparation method comprises the following steps: at first, adding sodium trimetaphosphate into the starch for reaction under the alkaline condition, regulating the obtained product to be neutral, and obtaining crosslinked starch after pumping washing and washing; then, preparing the crosslinked starch into crosslinked starch milk by using an acetic acid-sodium acetate buffer solution, adding beta-amylase into the crosslinked starch milk after high-temperature gelatinization for enzymatic hydrolysis, and performing high-temperature enzyme deactivation, alcohol dissolution, centrifuging, drying, crushing and screening to obtain solid powder which is the drug excipient. The drug excipient overcomes the defects of native starch and single modified starch, and the quantity of the other matters added in tablets as auxiliary materials is minimized, so that the drug preparation cost can be lowered, side effects of the drug are reduced, and the drug effect can be improved.