This study examines and analyzes how climate change affects flood discharges in the Han River basin. In order to consider climate change, this study uses the RCP 8.5 climate change scenario and predicts the probable rainfall for each frequency. In order to analyze flood discharges in the Han River, this study chooses the areas around the Soyang Dam, the Chungju Dam, and the Paldang Dam, and uses the HEC-1 model to predict the rainfall-runoff for each. The analysis reveals that the amounts of flood discharges in the areas around the Soyang Dam, the Chungju Dam, and the Paldang Dam will increase in two of the future periods(i.e., Future 1, from 2011 to 2040, and Future 3, from 2071 to 2100) in comparison to the reference period(i.e., 1981-2010), after showing a slight tip in Future 2(i.e., 2041 to 2070). As for the probability flood discharge, the amount is likely to increase overall throughout the experiment period(i.e., 2011 to 2100) in comparison to the reference period. In particular, the margin of increase will be especially greater around the Soyang Dam than around the other two dams. The increase in flood discharges reflects the increase in the amounts of rainfalls predicted according to the RCP 8.5 climate change scenario. Climate change, in other words, is expected to increase the future magnitude of flood discharges significantly, posing a significant challenge to the water management policy for rainy seasons.