Under certain parameters, a permanent magnet synchronous motor (PMSM) will exhibit nonlinear chaotic behavior, which is mainly manifested in torque and speed oscillation, resulting in unstable system performance. Under this background, a sliding mode control (SMC) experiment was carried out on an actual motor platform. After a reasonable process of data, the corresponding system phase diagram was drawn, and it was compared with that without SMC, thereby verifying the chaotic phenomenon from another point of view. Based on the analysis model of chaotic motion of PMSM, the chaotic dynamic behavior of PMSM was studied theoretically by using the stability theory and equilibrium point properties. It was found that the experimental results were consistent with the numerical simulation, which verifies the existence of chaos and the correctness of theoretical analysis and shows that SMC has a better inhibitory effect on the chaotic phenomenon.