Factors such as stator core saturation and armature reaction greatly affect the overload capacity of permanent magnet brushless DC motors (BLDC),which cannot meet the torque demand of foot-type robots in motion.A geared motor with high overload capacity was designed.From the key structural parameters of the motor,the effects of pole-slot fit,tooth-slot width and magnet thickness on the overload torque of the BLDC were analyzed;further,the finite element and response surface method were used to construct the optimization model of overload torque and torque fluctuation,and the improved beetle antennae search algorithm was used to carry out the multi-objective optimization design;the electromagnetic performance of the motor and the overload output torque before and after the optimization were compared and the effect of the planetary reducer structure on the motor was analyzed.Finally,to the prototype was developed according to the electromagnetic design,the torque speed test was conducted.The results show that the average overload torque increases from 1.99 N·m to 2.05 N·m after optimization,the torque pulsation decreases from 6.78% to 6.34%,which is reduced by 0.44%,and the motor overload output performance is better;the prototype experiments results are close to the simulation results,which verifies the reasonableness of the proposed method.