To address the issue of high torque ripple in permanent magnet assisted synchronous reluctance motor (PMA-SynRM), a multi-objective optimization design method based on the non-dominated sorting genetic algorithm II (NSGA-II) was proposed. First, the basic structure and working principle of the PMA-SynRM were introduced. Next, the rotor structure of the PMA-SynRM was improved by constructing air barriers and designing asymmetric auxiliary slots. Then, sensitivity analysis was conducted to identify the parameters that had the most significant impact on the optimization objectives of the PMA-SynRM, and multi-objective optimization was performed using NSGA-II. The optimal topology was selected from the generated Pareto front. Finally, the torque performance of the optimized motor was compared with that of the initial motor using finite element analysis software. Simulation results showed that the performance of the PMA-SynRM optimized through NSGA-II was significantly improved.