Carboxymethyl chitosan is an important water-soluble chitosan derivative, which has many medical effects, such as promoting wound healing, hemostasis, inhibiting scar, analgesic and antibacterial effects. In addition, it is also widely used in chemical industry, environmental protection and health care products. Carboxymethyl chitosan has good biocompatibility and biodegradability, and is widely used in hydrogels and wound healing biomaterials, and is also widely used in tissue engineering matrix materials; in addition, carboxymethyl chitosan is easy to be processed into nanoparticles, making it more suitable for drug delivery, bioimaging, biosensors and gene therapy; carboxymethyl chitosan also has many applications in green chemistry in recent years. Because of its unique biological properties, carboxymethyl chitosan has a wide range of applications in the fields of biomedicine and pharmaceuticals.