Abstract: The electric braking system of high-speed train uses dynamic braking in which the braking force is obtained by a resistor that radiates the energy obtained by operating the traction motor as a generator to heat, and regenerative braking in which the braking force is obtained by circulating the energy through a power line to a substation or another train. If excessive heat generated in the resistor during dynamic braking is not properly dissipated, the braking force will be reduced due to the malfunction, heavy loss and short circuit of the braking resistor. In this study, the resistance of the braking resistor that is used for the dynamic braking of high-speed trains was proposed to meet the design criteria by changing its structure and material. In addition, the temperature rise characteristics of the braking resistor due to the changes in current were analyzed by using a thermal analysis and the optimal structure and material were selected.