Many studies have qualitatively analyzed the response of hydrological characteristics to climate change in Haihe river basin, but quantitative research has been rare, which is essential for water resource management. To evaluate and quantitatively analyze the relationship between catchment runoff capacity and environmental factors, principal component analysis, step regression analysis, and sensitivity analysis were conducted. The results show that the runoff capacity of Haihe river basin was mainly controlled by vegetation types and soil texture; catchments with lower runoff capacity were mainly distributed in the upstream/northwest regions. In the catchments with middle runoff capacity, a 10% increase in precipitation (PRE), potential evapotranspiration (PE), and plant-available water coefficient (PAWC) would result in a 23.6% increase, 12.9% decrease, and 5.1% decrease in annual runoff, respectively, whereas in low runoff capacity catchments, a 10% increase in slope and leaf area index (LAI) would result in a 17.8% increase and 10.5% decrease in annual runoff, and in high runoff capacity catchments, a 10% increase in normalized differential vegetation index (NDVI) would result in a 12.6% increase in annual runoff. Soil conditions and vegetation configuration improvement in the upstream of Haihe river basin may contribute to the improvement of available water resources.