On account of the influence of human activities and climate change, the hydrologic series may change in time and space. Usually, the statistical method of F test is used to test change-point, but it can't be used to check out change-point. A slide F test of change-point analysis method is presented in this paper. Firstly, it test all of the points in the time series to get all possible change-points. Then, it chooses the point whose calculated F value is the maximum F as the probable change-point. The method has been used to analyze Chaobaihe River's 45 years annual runoff with the results from physical cause being confirmed, which shows that slide F test is better than traditional F test. It can be used to test and check out change-point. It is more effective in change-point analysis and the result is more reliable.