Aiming at the problem of torque ripple and radial electromagnetic force waves in the permanent magnet synchronous motor spindle whose permanent magnet poles are magnetized in parallel and the two sides are parallel,an optimization method of permanent magnet pole structure was proposed to suppress torque ripple and radial electromagnetic force wave.Based on the equivalent surface current method,an air gap magnetic field analytical model of the permanent magnet synchronous motor spindle with an arbitrary outer surface radius of the magnetic pole was established.The effects of rotor air gap magnetic field on torque ripple and radial electromagnetied force wave of stator slotted motor spindle were comprehensively studied.Under the premise that the minimum air gap length remained unchanged,the optimization objectives (the harmonics and amplitudes of the air gap magnetic flux density) were established,and the permanent magnet structure schemes (scheme 1 and scheme 2) that met different optimization objectives were obtained by iterative calculation.Finally,the validity of the analytical model of the rotor air gap magnetic field was verified by the finite element method.The rotor air gap magnetic flux density harmonics,torque ripple,cogging torque,average torque and radial electromagnetic force wave of the original structure motor spindle,the scheme 1 structure motor spindle and the scheme 2 structure motor spindle were compared and analyzed.The results show that the optimization method can be used to obtain permanent magnet magnetic pole structure schemes that meet different optimization objectives,and the comprehensive suppression of specified order magnetic flux density harmonics,torque ripple and radial electromagnetic force wave of the original motor spindle is realized.