The middle and lower reaches of the Liaohe River are located in the old industrial region of northeastern China and are important for food production and stockbreeding. Based on multi-temporal remotely sensed data from Thematic Mapper, this research attempted to reveal the spatial-temporal trends in land use and its impact on the eco-environment in middle and lower reaches of the Liaohe River. The results suggest that, in the last 15 years, the area of cultivated land increased and aggregated rapidly, while the area of woodland, grassland and water decreased considerably. The dominant land use change types were the conversion of woodland, grassland and wetland into cultivated land. The dynamic change of land use has had many effects on the local environment, including intensive soil erosion, increasing nitrogen content in the river and biodiversity loss in the region.