The failure of Hall sensors can give rise to loss of rotor position and speed information, which can result in loss of control of the speed loop, spatial decoupling errors, and affecting system stability in three-phase PMSM control system. To solve this problem, a Hall fault-tolerant control system based on sensorless state switching is proposed in this paper. Firstly, a three-phase PMSM control system based on FOC is established to analyze and clarify the importance of rotor position and speed signals. Secondly, a detection scheme based on Hall change edge signal is designed to detect the health status of Hall sensors and implement fault-tolerant state switching. For the stability of the system, a sliding mode observer is built to obtain the back electromotive force(back-EMF). In addition, the phase-locked loop is designed to extract the rotor position and speed information from the back-EMF. When the system enters a fault-tolerant state, changes in the speed feedback loop can affect the control performance of the system. Therefore, the speed loop PI parameter optimization scheme based PSO algorithm is proposed to optimize the performance of the fault tolerant control system. Finally, the effectiveness of the fault-tolerant method based on the sensorless state switching after particle swarm optimization is verified on a semi-physical platform (RCP-HIL). The experimental results show that the Hall fault-tolerant control system proposed in this paper can effectively detect Hall sensor faults and cut into the fault-tolerant control state, and can maintain the control system stable during fault-tolerant state switching. Furthermore, the control system can maintain an observation error of ±30 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rpm</i> under variable load or variable speed conditions at medium and high speeds when the system enters fault-tolerant control state.