Abstract: In order to explore the evolution law of the storm runoff ability of the Baihe River Basin, the Mann-Kendall trend test method is used to analyze the variation characteristics of the river basin's runoff capacity under the inter-annual and time-scale, and the influencing factors of rainfall and flow changes are diagnosed. The research shows that the annual precipitation, annual runoff and annual runoff coefficients show different degrees of decline. The main reason is that the increase of the underlying surface of the forest and grassland has strengthened the storage capacity of the small and medium-sized rainfall. The rainfall is mainly concentrated in the downstream Zhangjiafen area. The total rainfall in the rainstorm center exceeds 200 mm, the rainfall intensity exceeds 60 mm/h, the drainage area of the basin is about 510 km². The decrease of rainstorm frequency, the amount of groundwater extraction and the increase of forest area are the main driving factors for the reduction of river basin production and discharge.