With the recent increase in frequency of extreme hydrological events due to global warming and climate change, the number of natural disasters and the magnitude of damage associated with such disasters have rapidly increased in Korea. Floods caused the greatest damage among all natural disasters. In order to prevent this damage, there is a need of proper flood flow designing for dams and hydraulic structures considering climate changes. In this study probable annual maximum daily streamflow was computed through the frequency analysis of daily annual maximum flood and then further change in probable annual maximum daily streamflow was analyzed according to the future climate change by applying climate change scenarios. For this calibration and verification of parameters of rainfall runoff model was performed after analyzing the daily rainfall and discharge data observed at the major control point of Geum River watershed. After the extraction of RCP scenarios and new greenhouse gas scenario from the selected meteorological stations in the Geum River watershed, daily runoff was simulated by applying the SSARR runoff model. The independent test, homogeneity test and outlier test were conducted after configuring the existing measured annual maximum daily streamflow and annual maximum daily streamflow series calculated by the SSARR model. Results of L-moment ratio diagram and Kolmogorov-Smirnov test showed that among the GUM, GEV, GLO, GPA, GNO and PT3 distributions, PT3 distribution was found to be more appropriate compared to other probability distributions. Parameters of the PT3 distribution such as scale, location and shape were estimated by means of the L-moment method and then probable annual maximum daily streamflow of the target watershed was designed by using the estimated parameters of PT3 distribution. Variation rate was analyzed using climate change scenarios at the major control points of Geum River watershed. The findings of this study are expected to be used as basic data required for the hydraulic structures at Geum River watershed to cope with climate change in the future.