Cumulative anomaly curve and Mann-Kendall methods were utilized to do trend analysis of precipitation, potential evapotranspiration and runoff in the Xitiaoxi catchment of the Taihu Lake Basin. The results indicate that the runoff and potential evapotranspiration tend to decrease and precipitation occur without significant trend under the 95% confidence level. As to quantitatively discern the impacts of climate change and human activities on hydrological processes and detect the dominated driving force of hydrological variation, hydrological sensitivity-based method and double mass curve method with original and modified one were applied to distinguish the interference of climate change and human activities to hydrological processes in the basin during 1972~2010. It demonstrated that climate change and human activities contributed 37%~42% and 58%~63% to runoff variation in the basin, showing larger influence of human activities than that of climate change.