Abstract: This article describes the concept of base-system of water. It is also considered that the system is frequently adjusted,amended,and evolved. It is great important to correctly estimate its load capability and operational status,as well as to appropriately forecast its trend. For analyzing the base-system of water,the hydrological domain should be objectively extended,the hydrological technology need to be integrated,and fundamental theory researches and hydrological basic work both have to be strengthen.