The invention, which belongs to the engineering machinery field, discloses a high-speed permanent-magnet synchronous motor comprising a case, a stator iron core, a rotor sheath and a rotor permanent magnet successively from outside to inside. The rotor sheath has a cylindrical structure; the rotor permanent magnet has a cylindrical integrated magnetic steel structure; and the rotor sheath and the rotor permanent magnet are in interference fit connection. The stator iron core has a cylindrical structure; grooves are processed in the upper end surface and a lower end surface; and a stator armature winding winds around the grooves. According to the synchronous motor, on the basis of the reasonable stator and rotor structures and material designs, problems of losses and temperature rising as well as dynamics and statics problems of the rotor are solved. Moreover, the synchronous motor having advantages of simple structure and low losses can run stably at a high speed.