Currently, under the impact of climate change (CC), the phenomenon of extreme and against-the-order-of-nature weather appears more and more. Floods often occur suddenly, causing a great deal of damage to people and property. The South Central and Central Highlands have short and steep terrain and are also home to many small and medium reservoirs subjected to direct changes from the flow variation. There have been many studies and reports on the impacts of climate change on heavy rainfall in the area. However, there is some uncertainty between the results due to differences in input models, scenarios and destabilization methods. The paper focuses on assessing and analyzing the change of maximum rainfall in the South Central and Central Highlands under the average climate change scenarios (RCP4.5) and high climate change scenarios (RCP8.5) using different global climate models (GCM). The variation among the models (in percentile 25 to 75 percent) varied from 10 percent to 50 percent, indicating the uncertainty in the rainfall simulation of each GCM. As a result, flood simulation from the rainfall will be different according to the different climate models. The proposed report on the creation of zoning maps of design flood variation under the impact of climate change is based on the "consensus" of trends among GCM models. Based on that, the design floods in the basins in each region will be adjusted accordingly to ensure the safety and economics of the works