According to the national epidemiological survey of psoriasis, the average prevalence of psoriasis in China is 0.167%, of which 0.14% is in southern cities, 0.2% is in northern cities, 0.065% is in southern rural areas and 0.18% is in northern rural areas, and the prevalence rate in northern Yanbian is as high as 3.4%, while the prevalence rate in southern areas is only 0.05%. The above information shows that the prevalence of psoriasis in the north of China is higher than that in the south. And the urban area is higher than the rural area, and there is a significant difference. There are many reasons for the onset of psoriasis. The average temperature in the north is lower, and the cold time lasts longer in winter and spring, so people live and work indoors for a long time, and indoor doors and windows are closed for a long time, and the air does not circulate, resulting in muddy indoor air. At the same time, the human body’s resistance decreases in winter, and various harmful germs are easily transmitted, often causing respiratory tract infections and triggering and aggravating psoriasis. The northern winter climate is cold and dry, people are used to bathing less, the skin is dry and pruritic, so the skin lesions are more serious. In addition, winter days are short and nights are long. The short daylight exposure time is also not conducive to the fading of psoriasis lesions. In addition, in order to resist the cold, northerners often eat onions, garlic, chili and other spicy and stimulating foods and like to drink alcohol, which is also a risk factor for triggering and aggravating the disease. To sum up, the higher incidence of psoriasis in the north than in the south is related to geographical location, seasonal climate, living and eating habits.