Torque ripple is an important factor affecting the performance of motor. Aiming at the problem of large torque ripple in normal interior permanent magnet motors, an unequal magnetic pole combination method keeping the total amount of permanent magnet unchanged is proposed. The method makes the pole-arc length of a magnetic pole different from other magnetic poles to suppress torque ripple. The detailed derivation process and the determination method of magnetic pole parameters are given, and the performance is compared with the skewed slot structure. Aiming at the interior structure of the outer rotor, two magnetic isolation measures of magnetic bridge and magnetic barrier are compared and analyzed, and the finite element modeling method is established for simulation and verification of the structure. Finally, a 55 kW, 2 500 r/min motor is developed, and the experimental data are consistent with the simulation results, verifying that the proposed method has a significant weakening effect on cogging torque and back electromotive force (EMF) harmonics. It can effectively suppress torque ripple and improve the motor performance and has practical engineering significance.