The internal opening of a perianal abscess primarily refers to the anal crypt. It forms an infection site due to prolonged, repeated inflammatory infections, generally characterized by distinct pus discharge from the internal opening. Therefore, perianal abscesses tend to form a local internal opening near the anus along with intermittent pus discharge. If the perianal abscess acutely flares up or the pus cavity spreads, it might also rupture, causing pus to exit from an external opening, thereby leading to the formation of a typical anal fistula. During the acute phase of a perianal abscess, if there is local internal opening pain or pus discharge, it is recommended to seek surgical treatment as soon as possible. The primary method of surgery is aimed at radical treatment in one session. The principle involves opening the local pus cavity to allow for the discharge of pus, followed by a thorough debridement and removal of the local infection site. However, it is necessary to preserve the function of the local anal sphincter. If needed, a seton procedure may also be performed.