〔Abstract〕 Objective To discuss the application of magnetic resonance imaging (MRI)-3D model in syndrome of dampnessheat diffusing downward transsphincter anal fistula, in order to better understand anal fistula’s morphology, trend and the relationship with the sphincter and provide personalized auxiliary diagnosis and treatment. Methods A case-control study was conducted, 74 patients with syndrome of dampness-heat diffusing downward transsphincter anal fistula were confirmed by operation at Danyang Hospital of Traditional Chinese Medicine from January 2020 to June 2023, all had undergone MRI scans, among them, 37 cases underwent 3D modeling as the observation group and 37 cases did not undergo 3D modeling as the control group. The number of internal orifices, fistulas and the presence or absence of abscesses in two groups were recorded, the diagnostic sensitivity were calculated and analyzed. The surgical plan was designed according to the MRI results of the two groups, the fistula helaing status, surgical time, clinical and radiologic healing time between the two groups were compared. Results Operation and MRI examination results of the number of internal orifices, fistulas and the presence of abscesses and the sensitivities to detect them of two groups were compared, there were no statistically significant difference between the two groups (P > 0.05). There were no statistically significant difference in clinical unhealing rate, radiologic unhealing rate and healing rate between the two groups (P > 0.05). Among two groups of 12 unhealing patients, 8 were accompanied by abscess, of which 5 patients with clinical unhealing were all accompanied by abscesses, 3 of 7 patients with radiologic unhealing were accompanied by abscesses (1 of the 3 patients was in the control group, 2 cases in the observation group). The mean operation time of the patients in the observation group was shorter than that of the control group, and the difference was statistically significant (P < 0.05). There was no statistically significant difference in the mean clinical and radiologic healing time between the two groups (P < 0.05). The mean 3D modeling time of the observation group was (33.59 ± 6.73) minutes. Conclusion The MRI-3D model has high sensitivity in the diagnosis of the internal orifice, fistula and abscess of the syndrome of dampness-heat diffusing downward transsphincter anal fistula, and the personalized auxiliary diagnosis and treatment of MRI-3D model is helpful to shorten the surgical time.