The Liaohe River Basin is one of the seven largest river basins in China; along with the socio-economic development, water environmental problems have become increasingly prominent. Recovering and protecting the aquatic ecosystem has been considered as an important research for the development of northeastern region, most important of which is eco-water requirement. In view of the present main environmental problems in the Liaohe River Basin, based on the water resources districts, the types of eco-water requirement for river basins are identified. This paper raises that the eco-water requirement for river channels in dry seasons, sediment transmission water requirement in flood seasons, sea-entry water requirement, water requirement for groundwater recruitment and eco-water requirement for estuary wetlands are important components of the eco-water requirement for this watershed at present. Aimed at the characteristic of Liaohe River Basin as a seasonal river, the minimum flow method is developed to calculate the eco-water requirement for river channels in dry seasons. The eco-water requirement for each water resource district is calculated respectively, and the eco-water requirement of the whole river basin is calculated by adding up the above water requirements, with a deduction of the overlap between the trunk stream and the tributaries. As a result, the total water requirement of Lioahe River Basin is 130.44 10⁸m³or about 48.3% of the natural flow, of which the water resource districts of the Huntai and Dongliao rivers take up more than 60% of the natural flow, the Liaohe trunk stream about 53.5% and the others less than 50%. This paper can provide a scientific reference for water resources allocation and environmental protection of the river basin.