Originally Objective Method (OOM) and realtime dataset including trop ical cyclone path, strength and station precipitation are used to develop operat ional system of monitoring and impact assessment of tropical cyclone precipitati on. The system is composed of four functions: receiving of realtime tropical c y clone data, separating of precipitation caused by tropical cyclone, impact asses sment of tropical cyclone precipitation on water resource and social economy, an d display of figures. By introducing OOM technique and automatism of the operati onal system, the ability and efficiency of tropical cyclone assessment are impro ved greatly.