Background: The principal of management of anal fistula include closure of interior opening of fistula tract, drainage of contamination or necrotic tissue, and eradication of fistulous tract with maintenance of sphincter function. The selection of surgical operation (simple fistulotomy, fistulectomy, seton placement, development flap, fibrin glue or anal plug) is decided with the aid of the route of the fistula tracts and continence status. Objectives: The aim of the study was to determine the surgical technique “core out fistulectomy with anal sphincter reconstruction and primary closure of internal opening” in the treatment of trans-sphincteric fistula (high type or long tract) or supra-sphincteric fistula in terms of fistula healing, morbidity, recurrence and anal continence. Methods: This prospective observational study was carried out in the Department of Surgery Dr Amanat khan hospital and other private hospitals, Dhaka, Bangladesh, during 5th March 2020 to 10th April 2022. A total 30 patients between the age group 20 to 70 years who were diagnosed with Fistula-in-Ano(Complex Variety) which underwent Core out Fistulectomy with Anal Spincter Reconstruction and Primary Repair of Internal Opening. This analysis was done using SPSS 24 software version. The level of significance was set to 5% (p < 0.05). Results: There were 30 (91%) men and three (9%) women with a median age of 42 years. The common anal fistula type was high transsphincteric fistula in 31 patients with deep postanal abscess in two patients and two patients were suprasphincteric fistula. Conclusions: Core out fistulectomy with anal sphincter reconstruction and major closure of inner opening is a secure and nice method for excessive trans-sphincteric fistula. It has desirable useful results and no disturbance of continence. This has to be viewed in the cure of high trans-sphincteric fistula.