Abstract: Construction and operation of hydraulic projects have changed the hydrological regime of natural rivers and produced negative influences on river ecosystems. To improve and recover the deteriorated river environment, it is of great significance to analyze and make effective regulation of the ecological water demands by rivers. This paper describes a calculation model of these demands that was constructed through analysis of river hydrological regime and its influence on river ecosystem. This model takes river ecological restoration as its optimization goal and considers the demands and the economic and social water use. It adopts a multi-scheme simulation technique to simulate the demands under different regulation modes of dam and gate control on sluice-controlled rivers. Results show that the sluice regulation by the natural flow target highest aimed at ecological water demands can achieve better improvement on highly-affected hydrological indicators than that by the water allocation goal highest aimed at higher priority on social and economic water use, and thus it would offer a better support to healthy development of river ecosystems.