The problem securing water resources is nowaday one the most important problems. Therefore, dam reservoirs, having multipurposes which fulfil functions of water improvement and water control, have been constructing in one river system. Such system will need a method that can get the optimal solutions flood control for any floods logically, universally and rapidly. In this study, we try to analyze the flux mechanism of MATUBARA, SHIMOUKE DAM basins and KUSU RIVER and the remnant basins at TIKUGO RIVER, and try to discuss the problem of optimal flood control system by Dynamic Programming (DP) method.