In order to reduce the electromagnetic vibration and noise caused by the radial electromagnetic force, the electromagnetic vibration and noise performance of a interior radial permanent magnet synchronous motor for a vehicle is studied by using the finite element analysis method of electromagnetic field, structure field and acoustic field coupling. An optimization measure based on the offset of the magnetic bridge structure. The position of the magnetic isolation bridge of the motor is shifted to the magnetic pole direction along the circumferential track of the outer diameter of the rotor, and the adjacent distance between the magnetic isolation bridge and the length of the isolation magnetic bridge are optimized. Calculate the motor radial magnetic density amplitude, output torque average value, and ripple torque content under each structural offset distance, comprehensively consider the motor vibration and noise level and motor performance to determine the offset distance, and establish the motor stator iron The 3D finite element model of the core to calculate its natural frequency. The results show that this optimization method can effectively reduce the electromagnetic vibration and noise of the motor, and will not have a large impact on the performance of the motor. It can provide a reference for the optimization design of vehicle permanent magnet synchronous motor to reduce vibration and noise.