Abstract: OBJECTIVE To systematically review the latest research achievement in the preparation and the pharmaceutical applications of heparosan to provide a reference for its further research and development. METHODS The literatures at home and abroad were collected, summarized and analyzed on preparation methods of heparosan and its pharmaceutical application. RESULTS The present methods for the preparation of heparosan mainly included extraction from bacterial fermentation liquid, production by metabolic engineering bacteria and in vitro synthesis using recombinant enzymes. Heparosan could be used for the biosynthesis of non-animal derived heparin and preparation of non-anticoagulant heparin analogs as starting materials, as well as for drug delivery. CONCLUSION Heparosan has been produced at a large scale due to the successful application of fermentation engineering, metabolic engineering, and enzyme engineering, nevertheless, which still can't allow for tailored synthesis of heparosan with controllable molecular weight and its derivatives. To date, heparosan has been rapidly applied in the pharmaceutical field, and new strategies for the production and structure modifications will further expand its application in drug discovery and research.