The invention relates to a permanent magnet synchronous motor without a stator iron core, which mainly comprises a rotor shaft, an inner rotor iron core, a magnetic isolation block, a hollow cup stator (including a skeleton and a fractional slot concentrated winding), a Halbach permanent magnet and an outer rotor iron core, wherein the magnetic isolation block is embedded in the inner rotor iron core and forms an inner rotor core component part with the inner rotor iron core, the inner rotor iron core, the outer rotor iron core and the permanent magnet are all connected with the rotor shaft, the Halbach permanent magnet is stuck to the outer rotor iron core, and the hollow cup stator is fixed on a motor shell. The permanent magnetic circuit is formed into a closed loop circuit via the inner rotor iron core, the magnetic air gap, the Halbach permanent magnet and the outer rotor iron core. The invention utilizes the magnetic isolation block to achieve a salient pole structure of the motor so as to realize control by the difference of A-axis and D-axis inductance, the concentrated winding is utilized to weaken harmonic content in winding induced electromotive force and greatly increase the sinusoidal property of the winding induced electromotive force and winding current, so the torque impulse is reduced, and the stationarity of the output torque is improved.