Abstract: The Shiyang River basin is an inland river basin in the Hexi Corridor, Gansu province, northwest China. It is known for its scarce rainfall and fragile ecosystem. Water is a key facter to control the local ecosystem evolution and to constrain social-economic development. The reasonable allocation of water resources is the foundation of water resources sustainable utilization in the basin. Under the three criteria of ecosystem balance, efficiency and equity, a multi-objectives evaluation funcion of water resources allocation was established, in which the ecological objective was described as to satisfy the maximum ecological water requirement, economic objective was maximal net benefit, and social equity objective was minimum mean square error of variability of per capita net benefit for each calculating element. The water resources allocation scenarioes were set from different measurements, such as supply water, saving water, crop plant structure regulation and virtual water trade. The allocation results were obtained through the coupling model of the calculated unit optimal model and water resources transfer simulation model. And a water resources allocation scenario is provided by multi-objective evaluation function.