The impact of climate change on watershed water quantity and quality is one of the hot and difficult issues in the research field of climate change and water, especially the impact on water quality. In this study, the well-calibrated distributed water quantity and quality model was used to assess the impact of climate change in the Huaihe River Basin based on the daily precipitation and temperature data in climate scenarios generated through climate models. The spatial and temporal variations of water quantity and quality were simulated in the reference period (1990s) and future periods (2020s and 2030s). The impact of climate change on monthly water quantity and quality processes at the outlet of middle and upper stream of Huaihe River Basin, and the spatial distribution of runoff and pollution coefficients were analyzed. In addition, based on the spatial and temporal distribution characteristics of extreme precipitation during the specified paroxysmal water pollution incidents, the frequency and time of possible paroxysmal water pollution incidents in the future were deduced. Results showed that:1) The precipitation of the whole basin decreased in the A1B scenario of MPI model, while the temperature increased obviously with an extent of nearly 2 oC, leading to increasing evapotranspiration inevitably. Thus, the runoff magnitude at the outlet would decrease remarkably. The increasing of temperatures would increase the degradation of water pollution loads, and the decreasing of precipitation would also lead to a reduction of non-point source loads into the river, so the pollution load at the outlet would decrease. 2) In the perspective of spatial distribution, the average runoff coefficient would decrease in the future. The upstream regions of Shaying River and Guohe River would be highly affected by climate change. Due to the reduction of runoff coefficient, not only the frequency of water pollution in the basin would rise, but also the distribution of the contaminated areas would change. The most affected regions locate in the upstream regions of Hongru River, Shaying River and Jialu River. 3) If the pollutant emission level and operation rules of dams and sluices keep changed, the specified paroxysmal water pollution incident would happen in July 2035 during the periods of 2020s and 2030s, and its occurrence frequency would be about 20 years, which is much lower than the occurrence frequency of 3-4 years in the reference period. In conclusion, the impact of future climate change on water quantity and quality in the Middle and Upper Huaihe River Basin would be moderate. The study is expected to provide scientific and technical supports for adapting water pollution prevention to climate change in the Huaihe River Basin, as well as provide a certain reference for the impact assessment of climate change on water quantity and quality at the basin scale.