The invention discloses a preparation method of an enzyme-supported chitosan nanoparticle. The preparation method of the enzyme-supported chitosan nanoparticle comprises the following steps: (1) preparing a crosslinking complex of chitosan and enzyme; and (2) preparing nanoparticles by adopting an ionic gel method, stirring the crosslinking complex obtained in the step (1) by virtue of a magnetic stirrer, then dropwise adding sodium tripolyphosphate, obtaining a uniform opalescent suspension after reaction is finished, and then carrying out centrifugal washing for multiple times, so that pure enzyme-supported chitosan nanoparticles are obtained. The preparation method of the enzyme-supported chitosan nanoparticle has the advantages that firstly the enzyme-supported chitosan nanoparticle is good in stability, good in biocompatibility, high in drug loading rate and high in enzyme wrapping efficiency when used in an enzyme-precrusor mediation process; secondly, the preparation process is simple, reaction conditions are mild, convenience and rapidness are realized, ingredients are nontoxic, the drug encapsulation efficiency is high, and damage on protein molecules is small; and thirdly, chitosan nanoparticles wrap HRP (horse reddish peroxidase) inside, degradation of HRP in vivo is avoided, and a certain degree of controlled release is achieved.