The main three possibilities are: 1, hemorrhoids, is a common type of rectal perianal disease, when hemorrhoids repeatedly prolapse intestinal fluid can continue to stimulate the skin around the anus, causing chronic inflammatory changes, resulting in perianal itching discomfort, especially at night more obvious. 2, perianal eczema, for perianal skin allergic non-infectious diseases, mostly related to perianal moisture, clinical manifestations of perianal itching discomfort. 3, parasitic infections, common for rapacious worms more boarded in the large intestine, when the anal sphincter relaxed adult worms can crawl to the outside of the anus to lay eggs, resulting in anal itching. In conclusion, there are many causes of anal itching every night, when the anal itching occurs, should go to the regular hospital anorectal surgery or dermatology, clear causes and actively targeted treatment can be cured, will not cause serious clinical consequences.