Abstract: With incessant improvement in weather forecast technology, medium-term quantitative precipitation forecasts (MT-QPFs) become increasingly beneficial to medium-term forecasting of river runoff to achieve better accuracy. In this study, we have examined the application of MR-QPFs to the case of the Huanren reservoir on the Hun River. First, a Xinanjiang model and a multiple linear regression model were developed for medium-term runoff forecasting in flood and non-flood seasons, respectively. Then, real time precipitation forecasts with ten days leading time issued by the Global Forecast System (GFS) were applied to forecast the medium-term runoff of the Huanren reservoir. The results show that accuracy in these runoff forecasts decreases with leading time, and the accuracy of this model is higher than that of the traditional method.