High-speed permanent magnet synchronous motor has the characteristics of high power density, high control accuracy, not easy to heat, etc., and is widely used in many occasions. However, due to the small stator inductance and high current fundamental frequency, it brings a series of challenges to the motor control, and the traditional PI current regulator design method can no longer meet the control requirements of high-speed permanent magnet synchronous motor. In this paper, through the mathematical model of motor in d-q coordinate system, the complex quantity model of high-speed permanent magnet synchronous motor is deduced, and the current loop of high-speed permanent magnet synchronous motor is accurately modeled by considering the digital delay problem. Then the stability of the current loop of high-speed permanent magnet synchronous motor is investigated, and a design method of complex-volume PI decoupled current sensor with delay compensation is given. Finally, the results of the discretization study of the permanent magnet synchronous motor control system are simulated and verified in the Simulink platform.