The reasons for the reoccurrence of anal fistula after surgery are as follows: 1, improper treatment of the internal port: the vast majority of them are due to the fact that the internal port is not found accurately or the primary focus of infection, i.e., the internal port, is not completely removed. The most important reason for the reoccurrence of fistula is the following: 1. 3, fistula branch and its fistula cavity removal is not complete: that is, in the surgery did not scrape clean necrotic tissue or remove the branch, can lead to recurrence. 4. Complex internal orifice: when there are two or more fistula internal orifices, the search for the internal orifice is incomplete, leading to recurrence. 5. Newly generated anal fistula: Mostly, the patient has an anal gland infection and a perianal abscess, resulting in a new anal fistula, which is mistaken for a recurrence and is not difficult to identify in the clinic.