In this paper, we propose a method for the issue of identification for the variant pattern of hydrological series with variance variation: Breusch-Pagan test is used to check the inconsistency of the variance of the series, and Hydrological Variation Diagnosis System is designed to identify the variant pattern of variance. We take the third grade region on the upper reaches of Cetian Reservoir of Yongding River in the Haihe River as the study area, and discuss the variance variation of annual runoff series in this area. The result shows that the variance of annual runoff series in this area has a middle variation with a form of jump down in 1967, which is consistent with the real situation.