Runoff formation is affected by climatic change and human being activity,its process exhibits both trend change and abrupt change. First inter- annual and annual distribution laws of the runoff were analyzed at the Zhangze reservoir station in this paper,and it was discovered that runoff might lie in abrupt point. Then Mann- Kendall test and Lepage test were used to detect abrupt point of annual runoff time series. The results showed that the change point of annual runoff for Zhangze reservoir station occurred in 1977,runoff in the former period showed increasing trends and in the latter period showed decreasing trend both at 0. 05 significance levels. This abrupt change of annual runoff was probably impacted by human being activity. The conclusions provide scientific ground for planning and management water resource in this reservoir.