Abstract: Aimed at research meaning of the ecological water demand an example of Gonghe basin in Qinghai Province was presented and a further discussion to the calculation method of ecological water demand was made.The ecological water use has been carried on initial calculation,and the result showed the quantity of ecological water demands outside riverways is 5.3 million m³.The main part of which is used by artificial woodland,river system ecological water demand is of 352.3 million m³.Both of them are 357.6 million m³,accounts for 54.79% of the total water resources amount.With the result the ecological water demand has a specific gravity in available water resource.As an important part it should be brought into the research of the allocation of water resource so as to provide the basis for sustainable development of studied area where the ec-environment constantly worsens.At last the proposal was put forward that eco-environment construction of research area should primarily restore the degenerated pasture and change the pure arbor forest as to mixed forest with shrubs.