Erythrodermic psoriasis is difficult and severe in dermatology, with skin lesions spreading throughout the body and involving a large area of the epidermis. Professor Zhao Bingnan, the founder of Yanjing Zhao‘s dermatological school, believes that the disease is located in the blood, and the blood is divided into heat, toxin and Yin deficiency as the three key factors. This disease is mainly due to the blood accumulation of heat and fire, and then endogenously or externally triggered by toxic pathogens, the blood is divided into fire evil, the fire and poison are intense, which moves inward into the battalion and outward on the skin. In the later stage, the blood is mainly divided into Yin injury, and the positive Qi deficiency and evil is in custody. Professor Zhao Bingnan, starting from the blood division, always takes "clearing heat, detoxifying and nourishing Yin" as the main principle. With the development of the disease, he treats the disease in stages by clearing heat and cooling blood, reducing fire and detoxifying, clearing Ying and protecting the heart, nourishing Yin and Qi, and clearing away residual pathogens.