【Objective】 This study analyzed the variation characteristics and development of runoff in the upper reaches of Datong River basin to provide scientific basis for water resources planning and management. 【Method】 Cumulative anomaly,moving average,R/S method,Cramer method,and wavelet analysis were used to conduct stream features,tendency,detection for abrupt changes and period analysis. The reasons for runoff variations were also analyzed. [Result] (1) The annual runoff was mainly distributed in flood season with the ratio of up to 81.6% - 87.2%. The inter-annual runoff fluctuated significantly,experiencing wet year-dry year-wet year-dry year four cycles from 1956 to 2010. (2)The flows of Garide and Gadatan decreased by 0.010 2*10~8 m~3/a and 0.006*10~8 m~3/a,respectively for the past half century. The Hurst indexes of the two hydrological stations were 0.70 and 0.58,indicating that the decreasing trend had positive persistence. (3) According to the Cramer Test,a mutation was found in 1989 due to large area precipitation in flood season, and it had no continuity. (4) The principal periods of the stream-flow were 6 years, 18 years and 30 years. (5) Climate change was the primary reason for the reduction of runoff due to water diversion projects and human activities directly led to the decline of upstream runoff.【Conclusion】Affected by human activities and climate change, the runoff of Datong River basin upper stream has changed greatly, and attention should be paid to water resources utilization and management.