According to the problem of motor control precision caused by the cogging torque fluctuation, a robust design method of permanentmagnet DC micromotor cogging torque, which based on orthogonal experiment, was presented. For permanentmagnet brush DC micromotor, a 2D static magnetic field model of micromotor was established based on finite element software ANSYS. Taking noise factor such as tooth wedge angle error, and air gap length error, and calculated coercivity deviation into account, tooth width, tooth wedge angle, radius of slot bottom, permanent magnet center angle and calculation coercivity of permanent magnet were optimized synthetically in the condition of cogging torque fluctuation as smallerthebetter characteristic. Optimization result was analyzed by comparing to original scheme, the result show that noisesignal ratio of fluctuation amplitude of cogging torque increase by 43.5% for robust design. Therefore, fluctuation amplitude of cogging torque has a better robust for external disturbance.