Based on the annual runoff data from 1960 to 2014 in Miyun reservoir watershed,the change trend, abrupt time,periodic oscillations and the contribution of climate change and human activities were researched using the methods of cumulative anomaly,wavelet analysis and slope change ratio of cumulative quantity. The main results were showed as follows: ① There existed two abrupt point years in runoff: 1979 and 1998. ② The trend of runoff series varied over past decades,which was increasing before 1979,decreasing at first then increasing between 1980 and 1998,dramatically decreasing from 1999 to 2014. ③ The main periodic oscillations( 7 - year and 16 - year) existed in the annual runoff variation,which lasted from 1960 to 2000 and from 1960 to 2014, respectively. ④The contribution of climate change and human activities varied during different study periods: climate change was the key factor affecting runoff change before 1979,while the human activities ( 100. 26%) became the major reason from 1980 to 1998. Although human activity was the first important cause,the climate factor including precipitation( 12. 45%) and potential evapotranspiration( - 12. 38%) had evolved to a important reason from 1999 to 2014.