Psoriasis is a common chronic skin disease, commonly known as “psoriasis”. In 1984, China’s Psoriasis Research Collaborative Group found that the prevalence rate was 0.123%, and the current prevalence rate is on the rise. The symptoms of early psoriasis are atypical and the rash is polymorphic, so when diagnosing psoriasis, it is very easy to be confused with some other common chronic skin diseases such as eczema, seborrheic dermatitis, pityriasis rosea, ringworm, rheumatoid arthritis, furunculosis and many other diseases, resulting in untimely treatment or inappropriate choice of treatment methods, which delays the time of treatment for patients. Clinically, psoriasis can be simply divided into four types according to the different symptoms of psoriasis condition: common type, pustular type, arthritic type, and erythrodermic type. The key points of psoriasis diagnosis: Key one: understand the onset characteristics of psoriasis: psoriasis is a chronic skin disease, which can occur at different ages, with no major differences between male and female onset and a wide range of age of onset. The course of the disease is divided into a stable phase and acute phase, remission phase. The stable phase can be asymptomatic or with very few rashes, and the disease cannot be detected without careful examination; the acute and remission phases are called the active phase, with typical rashes or other manifestations. It is the key point to diagnose psoriasis according to the clinical manifestation features of the disease (easily shed scales on the basis of erythema, film phenomenon, punctate bleeding sign). Psoriasis vulgaris lesions can occur symmetrically in any part of the body. Key point 2: The type of psoriasis should be judged according to the different conditions of psoriasis: for example, psoriasis patients with secondary erythrodermic disease are called erythrodermic psoriasis. The rash with a small amount of exudate, with wet scales is called eczema-type psoriasis. Or if the rash starts as small pustules with fever and other symptoms, it is called pustular psoriasis. Combined with joint lesions, it is called arthritic psoriasis. The performance of psoriasis varies in different parts of the body, so you must go to a regular hospital and ask an experienced clinician for comprehensive treatment. Key point three: understand the initial onset of psoriasis: this is the most important point in the diagnosis of psoriasis, generally the initial psoriasis is good in the elbow, knee joint extensor and head, a few patients finger (toe) nail and mucous membrane can also be infringed. A few patients’ finger (toe) nails and mucous membranes can also be affected. An unprofessional physician may misdiagnose it as seborrheic dermatitis and onychomycosis. However, according to the typical clinical manifestations of psoriasis (erythematous scales, thin film phenomenon and punctate bleeding sign) and the patient’s medical history, an experienced professional doctor should be able to correctly diagnose the disease. The three points introduced above are the key points of psoriasis diagnosis, hoping to help clinicians patients diagnose the condition of psoriasis, and to remind patients that they must take measures to treat the disease in a regular hospital after it is diagnosed, so that the disease will not cause harm to the patient’s body.