Responses of water resources to human activities and climate factors, which is the basis to explore the hydrological processes and scientific management of regional water resources, has attracted more and more attentions in water resources research in recent years. Based on runoff data measured by Xiangtang hydroligical station in the Datong River Basin from 1950 to 2005, with temperature and precipitation time series, runoff change characteristics were analyzed by using linear tendency, 5 years moving average, accumulation anomaly, wavelet analysis methods. The effects of precipitation change and human activities on runoff were also studied quantitatively using double mass curve for annual rainfall stream flow. The results show that: (1) The annual runoff of the Datong River Basin was mainly contributed by those occurred from May to October with a proportion of 82.2%. Regression analysis shows that the Datong River Basin's runoff slightly decrease with time at a rate of -0.55·108 m3 /10a (P=0.249). The Hurst index is 0.58, which indicates that the decreasing trends of runoff in the Datong River Basin will continue in the future. (2) In recent 60 years, the Datong River Basin has different oscillation periods. In the time scale of 27a, the oscillation is mostly significant. The annual runoff will decrease after the year 2012, and will end up in the year 2020. (3) Using relational analysis and double mass curve analysis, we have obtained that mean annual runoff in the Datong River Basin is closely related to the annual rainfall before the year 1994. However, the human activities have become the main factor that causes the runoff decrease in the Datong River Basin after the year 1994 compared with annual rainfall. This paper considered the precipitation and human activities in driving forces analysis. In fact, evapotranspiration, LUCC and other factors should also be included. Therefore, the specific influencing factors of runoff changes need to be further studied.