Dynamic braking, which is frequently used in high speed trains, is a function and device that provides braking force using the electricity that is generated from a traction electric motor, and also dissipates heat from the lattice resistor that converts the current from the traction electric motor into heat. The heat from the lattice resistor, which is located in the motor block of a high speed train, damages the resistor wires and induces cracks in the insulators that affect the dynamic choppers, traction inverters, and electric motors during dynamic braking, and makes it difficult to control driving during acceleration or deceleration. In this study, the motor block lattice resistor, which was recently suggested to compensate for these problems, was designed, and experiments were performed on heat analysis simulation and temperature increase. Further field tests were performed to verify the advantages of the motor block lattice resistor.