Reducing the energy consumption of the whole vehicle requires multi-level collaborative optimization of “parts-system-whole vehicle”, and the improvement of the efficiency of electric drive (motor + controller) is a crucial link in reducing the energy consumption of the whole vehicle. Carrier frequency is an important parameter in motor control loop, which has an important influence on motor performance. In order to explore the influence of carrier frequency on the efficiency of the electric drive, this paper takes a passenger car electric drive as the object, modifies the code in the drive motor controller, explores the influence of different fixed carrier frequencies on the steady-state efficiency of the electric drive, formulates the variable carrier frequency control strategy on the basis of the fixed carrier frequency, explores the steady-state efficiency of the electric drive under the variable carrier frequency control strategy, and then uses the results of the steady-state efficiency to calculate the comprehensive efficiency and energy consumption of the electric drive under CHTC-C. The test results show that the strategy of changing carrier frequency has good effect for improving the steady-state efficiency of electric of electric drive and reducing the energy consumption of electric drive. In addition, at last, this paper makes an exploratory experimental study on the influence of two different modulation modes, CPWM and DPWM, on the efficiency of electric drive.