This paper focuses on the simulation and experimental study of the energy consumption and junction temperature performance of automotive motor controllers under various operating conditions, intending to improve the energy efficiency of new energy vehicles. By establishing models for typical operating conditions, efficiency map simulation models, and road spectrum simulation models, this research thoroughly examined the energy consumption performance of motor controllers under different conditions, including peak power points, full map operating efficiency, and the efficiency and temperature rise curves of the controller under actual driving conditions. The accuracy of the peak condition and efficiency map simulation results was validated through experiments. Furthermore, the study integrated real vehicle WLTC road spectrum data to derive the controller efficiency curve and junction temperature curve.