Abstract: Combined with principal component analysis, entropy methods and correlation analysis assess, the author assessed the aquatic ecosystem function of Liao River Basin of Liaoning Province. The indicators of aquatic ecosystem function and main driving factor were built. The author evaluated the aquatic ecosystem function and identified main driving factor based on the data during 2000 to 2010 of this basin. Results indicated that: awareness function was stronger than supply function, circulation function and habitat function, and the main driving factors included total amount of water resources, population, GDP, gross output value of agriculture, forestry and fisheries, tourism income and the amount of park. Results of this work would provide useful information for regional economic development and promote the comprehensive utilization and protection of the river basin.