Night ventilation is one kind of passive cooling ways which is very effective in certain climate type. The main work of this paper is to determine the cooling potential of office buildings that use night ventilation in the city of Xi'an. Xi'an is located in the Continental Climate zone of China. For this purpose, a typical office building simulation model has been built for the numerical analysis. Cooling and energy-saving potential of night ventilation in office buildings is determined through the simulation in different ventilation and air-conditioning cases by the energy simulation software DeST.