Based on the analysis of relation between rainfall and runoff, this study built a watershed runoff yield model based on runoff coefficient and determined the calculation formula of runoff coefficient. The model was applied in forecasting the runoff at the Dongwan station in the Yihe River Basin, Guanzhai station in the Shayinghe River Basin and Nianyushan station in the Guanhe River Basin. The results show that the forecasts in the 3 basins have met the eligibility requirements.