In order to get the YKK series motors to the ultimate purpose of achieving energy-efficient, and to meet the various request constraints set forth in the in the actual production, the paper introduces the niche genetic algorithm to the optimization of the motor design. For the forming structure of medium-sized high-voltage stator coils and the actual situation of three round relative fixed size, this article makes a corresponding improvements to the niche genetic algorithm, the proposed approach surmounts effectively the local convergence problem of standard genetic algorithm. The experimental results demonstrate that: compared with the initial program, the ultimate design results of the electrical motors meet the technical specifications of the proposed efficiency motor. Furthermore, the size of motor has been reduced, which saves the effective materials of the motor. It prove the feasibility and advantages of niche genetic algorithm’ improvement, and more important is, it verify the practical engineering value.