Land use/cover change and its effects on hydrologic processes are becoming an important aspect of global change research.In order to understand the effects of deforestation on hydrologic processes in theDaxing'anling area,a five-stage land use/cover date base in the Nuomin River basin since 1954was established based on remote sensing imagery data and topographic map.With GIS spatial analysis tools,the paperanalyzed the land use/cover change characteristics and its effects on hydrologic process.Results indicatedthat land use changed prominently in the Nuomin River basin during the past five decades.Forest and grassland decreased by 1 940.10and 748.99km²,respectively,and in contrast,cropland increased by 2 741.7km².Since the nature forest protection project came into force in the Daxing'anling area in 1998,woodlandreduction and farmland reclamation have showed a declined trend.Land use/cover change had effects on annual runoff and runoff increased during the late land use period with decreased forest and more cropland,andthe impact of land use/cover change on runoff was strengthened in response to increased rainfall.Besides,the effects of land use/cover change on runoff production were characterized by seasonal fluctuation.