The runoff of the Liaohe River Basin shows the significant decreasing trend in recent years,which seriously affects the ecological environment and sustainable development within the basin.In order to find out the variation characteristics of runoff and the relative influence of different influencing factors on the runoff changes,we calculated the average annual runoff,precipitation and evaporation in different sections of the basin based on the measured hydrological data during 19562015 and the observation data of nearly 40 meteorological stations within and around the basin.Then the inflection years in runoff changes for the different reaches of the river basin were obtained by the method of cumulative anomaly.Finally,we calculated the relative contributions of the precipitation,evaporation,and human activities to the runoff changes for different stages divided by the inflection years.The results showed that the runoff changes in the different reaches of the Liaohe River Basin were mainly influenced by human activities whose contributions exceeded 80% while the secondary factors were the precipitation and evaporation whose total contributions were basically less than 20%.In order to maintain the sustainable utilization of water resources and improve the ecological environment,it will need to formulate corresponding measures and accordingly to decrease the intervention of the human activities to the runoff changes of the river basin.