Chronic leg ulcer (CLU) is a common surgical disease. Its prevalence is 0.12 to 1.1% in the general population, is 0.5% to 3% in people older than 60, and reaches 5% in those over 80 years of age. According to the pathogenesis, it can be divided into vascular ulcer, diabetic foot ulcer, pressure ulcer, traumatic ulcer, neurotrophic ulcer, and malignant ulcer, etc. The wound healing stages include inflammatory response phase, hyperplasia phase and repair phase. Proper microenvironmental conditions can promote cell proliferation and migration, which is helpful for early wound healing and preventing inflammation and scar tissue generation. Ulcer wound treatment has a vital role in the wound healing process. At present time, the treatment for CLU mainly includes debridement and skin grafting, vacuum sealing drainage, anti-infection, local active factors, stem cell transplantation and dressing coverage, etc. The selection of appropriate wound dressings plays a crucial role in accelerating the wound healing of CLU. In addition to the good ability to absorb wound exudate, these dressings should also have the abilities of maintaining appropriate microenvironment, anti-bacteria, hemostasis, analgesia and other abilities for promoting wound healing. Chitosan is the product of partial deacetylation of chitin by the action of strong alkali. It possesses the characteristics of infection resistance, hemostasis, immune regulation, inducing tissue repair and cell proliferation, as well as good biocompatibility and biodegradability. At the same time, chitosan has effect on white blood cells and macrophages chemotaxis, enhancing macrophage phagocytosis, and stimulating neutrophils and macrophages to secrete interleukins and tumor necrosis factor, and thereby promoting "self-purification" of the wound surface. Chitosan has a good prospect in the treatment of CLU.