Small hole next to the anus without pain is considered to be mainly caused by the cause of anal fistula. Anal fistula is a pathologic tube that connects the anal canal or rectum to the perianal skin and is an infectious disease. It is usually a granulomatous inflammation that forms as a result of a perianal abscess that breaks down or is cut and drained. Usually the external opening of the fistula is located around the anus, the internal opening is in the anal socket, and the fistula of the fistula is between the internal and external openings. The external opening of the fistula is mostly granulomatous, if there is an acute attack of infection and lead to rupture of pus, it will form a small hole in the local area, which can be seen intermittent discharge of pus, blood, mucus secretion, accompanied by itching, moisture and other manifestations. It is difficult to heal by itself, as the perianal area is characterized by recurrent pus and swelling. When there is a small hole next to the anus and does not produce pain symptoms, it is recommended to go to the anorectal department of the hospital in a timely manner, under the guidance and help of the doctor, to formulate the best treatment plan, and actively carry out the treatment to avoid aggravation of the condition.