This paper takes Taihu Basin as a study area since it has highly intensive land use and is subject to rapid urbanization. Historical landuse scenarios in 1985 and 2000 are analyzed to track landuse changes by in-terpreting TM/ETM images. The L-THIA (Long-Term Hydrologic Impact Assessment) model is applied to estimate hydrological effects of landuse changes from 1985 to 2000, based on daily precipitation records span-ning 30 years (1971-2000). Results show that the main trend of landuse change is the urban expansion in the basin,which results in an increase of runoff volume of 1.14×10⁸m³, about 2.9% of the runoff volume from entire basin. Hydrological response varies with the extent of landuse changes in different parts of the basin. In Su-Xi-Chang and Pudong-Puxi sub-regions,with larger extent of landuse changes, the landuse changes result in runoff volume increases of 6.01% and 3.91%, respectively. In Hu-Su-Xi-Chang city zone, with intensive urbanization, the urban area expands as much as about 635.2 km² and the runoff volume increases by 6.5%.Based on runoff simulation and hydrological risk evaluation, the low, middle, and high risk areas are identified, which account for 37.5%,50.0% and 12.5%, respectively.