In the three-phase permanent magnet synchronous motor (PMSM) and its control system, the fault of the open or short circuit of the power semiconductor device, loss of the driving signal and the issue of the open circuit for cable connecting the PMSM and the inverter may often occur. This article proposes a fault-tolerant control strategy for the PMSM based on the four-leg inverter, which can maintain the stable operation of PMSM if there is a certain phase fault in the power semiconductor device, driving signal or stator winding. In the healthy mode, the 3D-SVM method is adopted to make four legs put into operation, and the neutral line current is used to compensate for the fault-tolerant operation of the PMSM in case of a certain phase fault. This article treats the PMSM, four-leg inverter and fault-tolerant control strategy as a system for simulation and analysis, which can obtain the variation rules of the internal magnetic field, loss and temperature field of the PMSM before and after fault tolerance. Furthermore, this article focuses on investigating whether the fault-tolerant operating condition will bring the potential negative impact of the PMSM thermal failure. Finally, the correctness of the analysis in this article is verified through experiments.