Disclosed is a permanent magnet synchronous motor. A rotor of the permanent magnet synchronous motor comprises a cylindrical iron core. The interior of the iron core is evenly provided with S-pole magnetic steel sheets with the number of P and N-pole magnetic steel sheets with the number of P in the axial direction, with P being a positive integer. The S-pole magnetic steel sheets and the N-pole magnetic steel sheets are alternately arranged. An internal hole is formed at the middle of the adjacent S-pole magnetic steel sheet and N-pole magnetic steel sheet in the axial direction inside the iron core. The utility model further discloses a rotor for the permanent magnet synchronous motor. The permanent magnet synchronous motor and the rotor thereof can reduce torque ripple caused by salient pole effect of the motor, improve the magnetic steel utilization rate of the motor, and enhance the anti-demagnetization performance of the magnetic steel with simple structure, easy production technology and low cost.