Abstract: The present invention relates to a process for preparing the controlled-release chitosan microcapsule, more specifically to a process for preparing the sustained-release chitosan microcapsule capable of releasing at an appropriate rate for a long time, which is characterized by: a) Biodegradable chitosan polymer is used for the capsule material; b) The capsule is kept stable during the release time by the rapid and effective crosslinking reaction between the chitosan polymer and the double crosslinking agent on the surface of tiny particles formed by a new emulsion interface reaction method using a double crosslinking agent of sulfuric acid and glutaraldehyde; and c) The microcapsule which is smaller than several &mgr;m s can be easily formed and the capsule is kept stable for a long release time because an insoluble polymer film whose source material is biodegradable is formed after the release.