Abstract: In case of large-scale emergencies, planned preparation can make the hospital more effective in coordinating the resources and responding quickly to the surging demand of patients. A simulation model based on SIMIO is established for the emergent public events, introducing the influence of the progressive progress of the patients and by simulation optimizing the operating room resource planning. Taking the Wenchuan Earthquake as the target subject, an investigation into the emergency process of a local hospital and a simulation experiment are carried out to rationalize the resource utilization rate and improve the treatment rate of the patients. The feasible surging capacity reserve plans are obtained by simulation in term of this scale of earthquake emergencies.