Fungal infection is not the cause of psoriasis. The cause of psoriasis has not been clarified yet, and it may be related to genetic, environmental, immune and other factors. 1. Genetic factors: psoriasis has a genetic predisposition. Research shows that about 30% of psoriasis has a family history, and the heritability of first-degree and second-degree relatives of psoriasis is 67.04% and 46.59% respectively. When one of the parents suffers from psoriasis, the incidence of psoriasis in their children is about 16%; and when both parents are psoriasis patients, the incidence of psoriasis in their children is as high as 50%. 2. Environmental factors: only genetic background is not enough to cause the onset of psoriasis, environmental factors play an important role in triggering and aggravating psoriasis. The factors that are most likely to trigger or aggravate psoriasis are infection, mental stress, stressful events, trauma, pregnancy, obesity, alcoholism, smoking and the effects of certain drugs. The onset of psoriasis is often associated with acute streptococcal infection of the pharynx. 3. Immunity factors: T lymphocyte abnormal activation, infiltration in the epidermis or dermis is an important pathophysiological feature of psoriasis, which indicates that the immune system is involved in the occurrence and development of the disease. Current studies have shown that the occurrence of psoriasis has no relationship with fungal infections. If patients are diagnosed with psoriasis, it is recommended to go to regular hospitals for standardized treatment in time to avoid delaying the condition.