The present application relates to a permanent magnet DC motor, which comprises a stator assembly and a rotor assembly, wherein the stator assembly comprises a housing and a magnetic cylinder, and the rotor assembly comprises a rotor; the rotor, the magnetic cylinder and the housing are sequentially arranged from inside to outside; the ratio of an angle corresponding to a commutation section of the surface magnetic curve of the magnetic cylinder to the corresponding angle of the surface magnetic curve of the corresponding magnetic pole is less than or equal to 15%; and the outer peripheral contour of the magnetic cylinder is based on a regular polygon, and curves are arranged at the connections of sides of the regular polygon to smoothly connect the sides of the regular polygon. The motor of the present application reduces the noise and vibration of the motor and improves its EMC level.