During the last decade,research on ecological use of water(EUW)has been greatly pro-gressed.The various concepts of EUW were propounded,such as the versions of physical geogra-phy balance and ecosystem stability etc.But the unified concept has not been conformed until now.According to the connotation of EUW concept,the various combinations of the six terms(e-cology,environment,eco-environment with use of water,water requirement,water consumption)can be merged into two terms:ecological water requirement and ecological use of water.EUW of zon-al vegetation is the basic research of EUW,which can provide scientific basis and goal for eco-logical conservation and vegetation construction.The definition of EUW concept can be suggested as follows:For maintaining normal devel-opment and relative stability of various kinds of ecosystems,the water which has to be consumed by the ecosystem and has to exist in the ecosystem is called ecological use of water(EUW).