Abstract: Surgical operation scheduling determines the start time of individual surgical operations and assigns the required resources to each surgical operation over a schedule period in considering several constraints related to a complete surgery flow and multiple resources involved. This task plays a decisive role in providing timely treatments for the patients while hospital resource utilization is balanced. To integrate the surgical operation scheduling problem with real-life nurse roster constraints, such as their role, specialty, qualification, and availability, a mathematical model is proposed and an ant colony optimization (ACO) approach is used to efficiently solve the problem. A two-layer nested ACO structure and relative pheromone updating strategy is designed. A test case from the literature of a daily nurse scheduling problem is presented and the performance of nurse assignments by the ACO is compared with the method used in the literature. Result shows that the proposed ACO can satisfy not only nurses'various constraints in operations research (OR) management, but also achieve good results in shortening the end time, reducing the nurse overtimes and balancing the resource utilization in general.

Key words: surgical operation scheduling, ant colony optimization, multi-resource constraint, nurse roster