The permanent magnet synchronous motor with high-efficiency and high-power density is widely used in the electric propulsion system of underwater vehicles,and the rotor position sensor is required to achieve its high performance control. The adoption of Hall-effect position sensor can save the volume,but the low-resolution position signal cannot meet the high-performance control needs of the motor. In this paper,the real-time rotor position is estimated by linear interpolation method based on Hall position signals and average speed,and used in the vector control of permanent magnetic synchronous motor. Aiming at the sudden change of the estimated position at the correction point caused by Hall signal deviation,by improving the smooth position estimation value of the average speed calculation and position correction method,the current distortion caused by the sudden change of the estimated position is suppressed,and the low-noise operation of the permanent magnet synchronous motor for propulsion of the underwater vehicles is realized. The experimental results verify the feasibility and effectiveness of this method.