According to the working condition and water quality of the circulating refrigerated water in the central air conditioner, the formula selection in the lab has been carried out and the suitable treating technology and chemicals have been found. Throught industrial application, it shows that the corrosion of pipeline in the system can be controlled, the load of refrigerator can be decreased and the energy consumption can be lowered and the equipment life can be prolonged. So the efficiency of heat transfer can be increased. In addition, the treatment expense is cheap and the operation is simple. Thus, much trouble can be avoided the maintenance cost can be saved. This techonlogy can give a satisfactory result in the water saving, energy saving and stable operation.