Objective:To observe the clinical efficacy of sphincter preservation in the treatment of posterior anal canal abscess. MethodsOne hundred and thirty-four patients with posterior anal canal abscess were randomly assigned into treatment group (70 cases) and control group (64 cases). The control group was treated with stage I radical operation for perianal abscess and the treatment group was treated with sphincter preservation. The clinical efficacy was observed, and the postoperative VAS pain score of wound, wound granulation growth score, postoperative anal function score and the time to exfoliation of septic tissue, disappearance of exudate and wound healing were compared between the groups.  Results:①The total effective rate was 95.7% and 92.2% in the treatment group and the control group, respectively. The clinical efficacy was superior in the treatment group to that in the control group (P<0.05). ②At 3,4, 5 and 6 days after operation, the VAS pain score of wound was lower in the treatment group than in the control group (P<0.05). ③In the treatment group, the time to exfoliation of septic tissue, disappearance of exudate and wound healing was shorter in the treatment group than in the control group (P<0.05). ④At 7,4 and 21 days after operation, the wound granulation growth score was lower in the treatment group than in the control group (P<0.05). ⑤At 1 and 6 months after operation, the anal function score was lower in the treatment group than in the control group (P<0.05).  Conclusion:Sphincter preservation is effective in the treatment of posterior anal canal abscess, effectively protecting anal function, reducing postoperative pain and shortening the time to wound healing.