Abstract: The modified chitosan magnetic nanomaterials, which was prepared by the composite of modified chitosan and magnetic materials, retains the strong chelating ability of chitosan with metal ions, and have good regeneration performance. These two properties greatly expand the application prospect of chitosan. This article focuses on the preparation methods of modified chitosan nanomaterials, and the latest research and application progress in wastewater treatment, immobilization of active substances, medicine and medical treatment, etc, which is to provide some theoretical support for the development and utilization of chitosan resources.