To reduce the size of wheel motor of micro electric cars and improve the sensitivity of parking brake systema new structure using electromagnetic clutch embedded in wheel motor to brake in lose electric is designedand the electromagnetic clutch is optimized and dynamically analyzed.Based on genetic algorithmelectromagnetic clutch structure parameters are designedand electromagnetic attraction force is optimized.Optimization results show electromagnetic attraction force increases by 27.6 N.Based on the finite element methodthe current curvesuction curve and displacement curve are analyzed.The results show electromagnetic attraction force and dynamic response time both meet the requirement of parking brake of micro electric cars.