The MTPA control strategy of traditional virtual injection method IPMSM is proposed to solve the problem of slow dynamic response due to the complex coordinate transformation process and the cascade of band-pass filter and low-pass filter in signal processing. Firstly, in the virtual signal injection process, the high frequency signal is directly injected into the id and iq obtained by sampling and filtering, which simplifies the complex root operation process. Secondly, a new MTPA criterion formula is derived according to the improved virtual signal injection method. After demodulation of the high frequency response signal, the optimal current vector angle is obtained through the low-pass filter and integrator in turn. Finally, the effectiveness of the improved virtual injection method was verified by simulation and the 8.4 kW built-in PMSM experimental platform. The experimental results show that the improved virtual injection method can effectively simplify the calculation, and still has strong robustness after eliminating the cascade response. The loading experimental speed overshoot is only 3 r/min (0.375%), and the dynamic response time is improved by about 0.2 s.