Typical symptoms of patients with anal fistula are perianal pus, pain, and itching. There is no mass outside the anus, and if there are no other symptoms, anal fistula is not considered. Most patients present with anal fistula, is caused by perirectal anal canal abscess, anal fistula is composed of three parts, external opening, internal opening, fistula. The causes are complex, such as long-term sedentary, overtime and late at night, lack of sleep, drinking alcohol, eating spicy and irritating food, long-term constipation, diarrhea and so on may form anal fistula. Secondly, a history of perianal abscess, Crohn’s disease, malignant tumors, ulcerative colitis, extra-anal infections can also cause anal fistula. Patients with anal fistula have more obvious symptoms, mainly manifested as an external opening in the perianal skin with purulent secretion, intermittent episodes, stimulated by long-term secretion, may lead to anal skin itching. If pus forms in the fistula, it can form obvious localized swelling and pain. To summarize, anal fistula is a disease belonging to the anal area, and the patient’s symptoms are more obvious. If there is no lump outside the anus or any uncomfortable symptoms, it is not considered to be caused by anal fistula. If in doubt, please go to the hospital for consultation.