On the basis of the successful experience of artificial precipitation experiment summarized at Zhexi Reservoir during many years, the climatic characteristics, the situation of flood control, the electrical power requirement and the safe production requests over the Zishui Basin are analyzed, and the suitable time period of artificial precipitation operation at Zhexi Reservoir are defined. According to the analysis of 37 synoptic cases and precipitation characteristics of the typical precipitation day in the recent five years, the main cause for precipitation is attributed to the westerly system, easterly system and orographical clouds. Moreover, the optimized layout and operation mode of artificial precipitation operation at Zhexi Reservoir are proposed. After discussing a typical example of torrential rain leading to flood in the reservoir area, we found that the artificial precipitation operation at Zhexi Reservoir needs avoiding the high risk areas of the heavy rainfall caused natural disasters. The effect and benefit of artificial precipitation operations at Zhexi Reservoir are significantly increased throught practical application, and this method is available for reference to artificial precipitation experiments at other large reservoirs.