Operating rooms (OR) is one of the most demanding department in hospital. OR’s process will directly influence the profits of hospital as well as the patients' satisfactory degree. On the condition of a complex cooperation of ORs with variations, simulation has its advantage on solving problems. From the perspective point of rational utilization of resources, the simulation modeling of OR in big hospital by a latest simulation platform – SIMIO is proposed. The modeling objects and the logic underline are studied, and a simulation model case is presented.