The invention provides a forced air cooling high-frequency permanent-magnetism synchronous motor with high power density, which relates to the technical field of motors. The invention solves the problems of low reliability, poor cooling performance, large high-frequency loss of a fixed rotor of the motor and unreasonable loss distribution existing in the traditional high-frequency permanent-magnetism synchronous motor. The motor comprises a casing, an end cover, an armature component, a rotor and a rotor supporting bearing, wherein the casing is provided with an axial cooling ventilation ductof a stator, and the end cover is provided with an axial vent hole; the armature component mainly comprises a stator core, an armature winding, an insulator and a slot wedge, wherein the outer surface of the slot wedge and the two side faces of a notch are smooth along an axial direction, do not have a barrier and form an axial cooling ventilation duct of the rotor. The rotor comprises a permanent magnet, a rotating shaft and a sheath of the permanent magnet. The synchronous motor can be used as a high-speed motor, can also be used as a high-speed generator and has extensive application prospect.