Streamflow in many rivers has changed recently under global change, which is dominating the water management strategies.It was attributed to climate and underlayer change,including the increase in water consumption.The identification of anthropogenic element in streamflow change is very important and increasingly required for water management planning and climate mitigation and adaptation actions.A framework was proposed to attribute streamflow change in terms of three-source of climate variablity, anthropogenic climate and basin underlayer change.Projections of climate change effects in streamflow were deduced by scenarios of IPCC AR5 in Zhanghe catchment, China.The results suggest that the role of basin underlayer change overwhelm climate change in recent historical period, while the internal climate variability would not be negelected since it could exacerbate or ameliorate the impact of climate change in the near future.As a fundamental source of uncertainty, the effect of internal (stochastic) climate variability would be comparable or larger than the projected climate change signal.