As a resourceful, new and natural macromoleculer compound and a kind of polyose compounds, chitosan was considered as a good pharmaceutical releasing carrier for lots of properties, such as sound tissue compatibility, various biologic activity, low toxicity, easy absorption, etc. Here, the biological properties, types and clinical application of chitosan as drug controlled release carrier, particularly its application as gene carrier, were introduced. Besides, the directions for future development of chitosan as drug carrier were forecasted.