PMSM emulators are widely used in the development and testing of automotive electric drive systems, offering numerous advantages such as low energy loss, high flexibility, and safety. However, existing PMSM emulators do not fully consider PMSM harmonics and the torsional vibration characteristics of the transmission system, which limits their testing accuracy. Therefore, this article first uses finite element analysis to obtain numerical solutions for PMSM torque ripple under the influence of factors such as slotting, core magnetic saturation, and non-sinusoidal magnetic fields. Based on the periodicity of torque ripple in both time and space dimensions, an accurate analytical model of PMSM torque ripple for any stator current excitation is established. Secondly, focusing on the current mainstream three-in-one electric drive system of pure electric vehicles, a multi-degree-of-freedom dynamic model of the transmission system is established using the lumped parameter method to analyze the torsional vibration frequency distribution under the action of torque harmonics. Thirdly, a high-efficiency PMSM emulation control system with current input and voltage output is proposed, incorporating the harmonic-considered transmission system model into the motion segment of the simulation system. Finally, through simulation, the application effects of the emulator under different working conditions are validated. The results show that the emulator constructed in this article can more effectively characterize the electromechanical coupling characteristics of the transmission system, greatly improving the simulation accuracy of the electric drive system during large torque steps and low-speed start-up processes.