Objective:To investigate the therapeutic effect of open suture and selective suture in patients with high complexity anal fistula and its effect on anal function and complications.Methods:Prospectively selected 174 patients with high complex anal fistula who were hospitalized in the Anorectal Surgery Department of the Second People′s Hospital of Yibin City from December 2018 to December 2021 as the study subjects, including 138 males and 36 females, aged from 26 to 45 years, with an average of (35.20 ± 8.86) years. According to the admission order of patients, grouped them into single and double numbers, with single numbers being the control group ( n=87) and double numbers being the observation group ( n=87). The control group was treated with traditional incision and thread hanging therapy, while the observation group was treated with selective suture through incision and thread hanging therapy. Compared the surgical time, blood loss, surgical cost, wound healing time, and anal function at 6 months after surgery between the two groups of patients. Compared the treatment effects of two groups of patients at 6 months after surgery. Compared the postoperative complications within 6 months and recurrence within 1 year between the two groups. The measurement data subject to normal distribution were expressed by mean ± standard deviation( ± s). The two groups were compared by independent sample t test, and the count data were compared by Chi-square test. Rank sum test was used for comparison of hierarchical data. Results:The surgical time in the observation group was higher than that in the control group [(44.30 ± 8.11) min vs (42.18 ± 7.25) min, ( t=-2.44, P<0.05], and the surgical cost was higher than that in the control group [(1184.81 ± 372.68) yuan vs (835.28 ± 320.03) yuan, t=-8.75, P<0.001]. There was no statistically significant difference in blood loss data between the two groups [(19.57 ± 6.07) mL vs (18.35 ± 5.25) mL, t=-1.88, P>0.05]. The length of wound healing time in the observation group was lower than that in the control group [(24.18 ± 4.35) d vs (29.35 ± 5.08) d, t=11.09, P<0.001]. The anal function score of the observation group at 6 months after surgery was lower than that of the control group [(4.80 ± 1.21) score vs (6.71 ± 1.35) score, t=14.72, P<0.001]. All patients did not experience any loss of follow-up. In the comparison of treatment effects 6 months after surgery, the observation group had a better efficacy rating than control group ( Z=3.86, P<0.001). At 6 months after surgery, the incidence of complications in the observation group was lower than that in the control group [2.30% (2/87) vs 10.34% (9/87), χ2=4.76, P<0.05]. One year after surgery, the recurrence rate in the observation group was lower than that in the control group [2.30% (2/87) vs 10.34% (9/87), χ2=4.76, P<0.05]. Conclusion:The application of incision and thread-drawing selective suture in the treatment of patients with high complex anal fistula is beneficial to the treatment effect of patients, reduces postoperative complications, and protects the anal function of patients, with good use value.