Introduction: Surgery cancellation is of the most important causes of hospital inefficiency as well as resource wastage. This study was conducted to determine effective factors and causes of surgery cancellation, and to identify areas to reduce it in a hospital using improved management method. Methods: In this descriptive study, effective factors on surgery cancellation and effective strategies for reducing it in Farabi hospital, Tehran, Iran, were extracted and were screened by using geometric mean and excel software. Fuzzy Analytic Network Process (FANP) and Fuzzy Decision Making Trial and Evaluation Laboratory (Fuzzy DMATEL) were used for weighing the factors. By using brainstorming and VIKOR methods, the model was designed and was applied using Find, Organize, Clarify, Understand, Select-Plan, Do, Check, Act (FOCUS-PDCA) method. Results: Missed appointments by patients, fever, colds, and other factors, respectively, had the highest percentages among the causes of cancellation. According to the ranking, "cross-sectoral coordination", "improvement of preoperative counseling", "personnel training", "programming to prepare supplies and equipment", and "patient education" ranked first to fifth to reduce surgery cancellation. By applying FOCUS-PDCA method, the number of surgery cancellations decreased in the first 6 months of 2018 compared to the same time in 2017. Conclusion: Carrying out FOCUS-PDCA methodology decreased surgery cancellation in Farabi hospital. Setting up program for operating room regarding the type of surgery and potency of surgical management, and precise monitoring on the process of preparing the patient before surgery were suggested to improve the quality and management of the operating room.