Psoriasis (alias: psoriasis, English: psoriasis) is a common chronic inflammatory skin disease, the Chinese medicine called “white mange”, with “skin like rash scabies, white and itchy, scratching up the white skin” name. In mild cases, it can be manifested as a few silver-coin-sized plaques on the elbows and knees, while in severe cases, the whole body can be affected. Its pathophysiological mechanism is mainly for the abnormal epidermal proliferation and differentiation and the activation of the immune system. 1. Genetic factors: it is a polygenic genetic disease with the interaction of genetic factors and environmental factors. 2. Immune factors: In recent years, it has been recognized that psoriasis is an immune or inflammatory-mediated disease. 3. Infectious factors: research has confirmed that streptococcal infection, Staphylococcus aureus infection and fungal infection are related to the development of psoriasis, but whether viral infection is related to the development of psoriasis has not been clarified. 4. Endocrine factors: pregnancy can make the lesions disappear or reduce, or make the lesions aggravate. Thyroid disease, diabetes and other endocrine diseases do not have a significant impact on the disease. 5. Mental factors: patients can have neuropsychiatric changes, and these changes can aggravate existing lesions. 6. Lifestyle, medication, and environmental factors. Studies have found that exposure to moisture, infection, alcohol, medication and stress are the main risk factors for psoriasis. Drugs that may induce or aggravate psoriasis include β1-blockers, non-steroidal anti-inflammatory drugs, lithium salts, anti-malarials, tetracycline, calcium channel blockers, metformin, interferon alpha and so on. Environmental factors are related to the age of onset, and seasons and climate have an impact in the onset and recurrence of psoriasis. A team of experts study that the cause of psoriasis lies in the wind evil into the blood. Or due to the attack of external evils, or due to internal heat and wind, resulting in wind and blood heat and blood dryness, the skin loses moistening, metabolism is out of order and the skin lesions are regenerated, the scales fall off and itching is intolerable; over the long term injury to the body fluid, and the evils enter into the collaterals, which results in stagnation of collaterals and prolonged and difficult to be cured.