Abstract: 【Abstract】 Psoriasis is an immune-mediated chronic, recurrent, inflammatory, systemic disease induced by the combination of heredity and environment. Psoriasis is a non-communicable disease, its typical clinical manifestations are limited or widely distributed scaly erythema or plaques. Its treatment is difficult, and patients usually need lifelong treatment. The etiology of psoriasis involves heredity, immunity, environment and other factors, which may induce excessive proliferation of keratinocytes or inflammation of joint synovial cells and chondrocytes via the immune response mainly mediated by T lymphocytes and various immune cells. In the theory of traditional Chinese medicine （TCM）, it is believed that psoriasis is mostly caused by hot toxic blood, loss of nutritional ingredient in blood, blood perfusion stasis, dry wicked wind in the body and skin system imbalance. Psoriasis is an incurable disease, and many drugs and regimens are available for its treatment at present. Choosing appropriate drugs and regimens is very important for patients with psoriasis to control disease progression and maintain long-term efficacy. The purpose of guidelines is to gradually standardize treatment, improve treatment effectiveness, and to minimize adverse effects as far as possible. Treatment protocols of psoriasis should be determined based on patient′s symptoms. Patients with mild psoriasis can be mainly treated with externally applied agents, those with moderate to severe psoriasis can be treated with systemic medications, and targeted biological agents can be appropriately chosen for those resistant to traditional systemic treatment. The main aim of psoriasis treatment is to control symptoms and improve the quality of life. With continuing development of novel drugs and regimens for psoriasis, we update guidelines to timely introduce new international and national achievements to domestic physicians, so as to keep pace with global progress in this field. Compared with the previous two editions of guidelines for diagnosis and treatment of psoriasis in China, some contents are supplemented and revised in this edition, which will further facilitate standardization of diagnosis and treatment of psoriasis in China, increase the efficiency of diagnosis and treatment, and improve the quality of life of patients.

Key words: Psoriasis, Diagnosis, Treatment, Guidelines