In recent years with the sustainable development of economy, the energy consumption of air conditioning system has accounted for over 40% of the total of buildings in China. Energy conservation has become an important issue. Various energy wastes exist in the operation process of central AC systems. So the central air conditioning system of energy saving has great potential. Central air conditioning load changes with time-varying characteristics, the load and operating conditions are influenced by various factors such as season, weather, traffic and environmental conditions changing and so on. They are always changing, and always fluctuating. Even in the day, morning and evening have temperature changes. According to statistics it is only a short time for the occurrence of most buildings’ maximum load time, and air conditioning systems are running at part load conditions in most time. If air conditioning system operating control way cannot change load according to the dynamic adjustment, which necessarily causes enormous energy waste. In this paper, with the help of a typical building located in Baoding, China, the simulation of a central air-conditioning system was carried out. First, the simulation models of main equipments of a central air conditioning system are established. Second, according to the actual loads, simulation of the different energy control modes and the operation schemes were carried through. Third, the simulation curves were obtained. Finally, based on the comparison of simulation curves, the optimal energy saving control mode and the operation scheme of the central air conditioning system were analyzed, the energy saving potentials existing in the actual operating process were proposed. All these above will be very important for the AC system operation optimization of building energy-efficient and air conditioning system operation and management.