Abstract: Using monthly streamflow data from the 1960–2000 period and annual streamflow data from the 2001–2014 period, and also meteorological data from the 1960 to 2014 period from 815 meteorological stations across China, the Budyko-based hydrothermal balance model was used to quantitatively evaluate the fractional contributions of climate change and human activities to streamflow changes in ten river basins across China. Particular importance was attached to human activities, such as population density and Gross Domestic Product (GDP), and also water reservoirs in terms of their relationship with streamflow changes. Results indicated that: (1) streamflow changes of river basins in northern China were more sensitive to climate change than those of river basins in southern China. Based on the degree of sensitivity, the influencing factors to which streamflow changes are sensitive included: precipitation > human activities > relative humidity > solar radiation > maximum temperature > wind speed > minimum temperature. Hence, it can be argued that hydrological systems in northern China are more fragile and more sensitive to changing environment than those in southern China and hence water resources management in northern China is more challenging; (2) during 1980–2000, climate change tended to increase streamflow changes across China and have a dominant role in streamflow variation. However, climate change tends to decrease streamflow in river basins of northern China. Generally, human activities cause a decrease of streamflow across China; (3) In recent years such as a period of 2001–2014, human activities tend to have increasing or enhancing impacts on instream flow changes, and fractional contributions of climate change and human activities to streamflow changes are, respectively, 53.5% and 46.5%. Increasing human-induced impacts on streamflow changes have the potential to add more uncertainty in the management of water resources at different spatial and temporal scales.