The invention discloses a permanent magnet synchronous motor. A rotor of the permanent magnet synchronous motor comprises an iron core. The iron core is cylindrical. P S-pole magnetic steel sheets and p N-pole magnetic steel sheets are evenly arranged around the axis in the iron core, wherein p is a positive integer. The S-pole magnetic steel sheets and the N-pole magnetic steel sheets are arranged at intervals. Two d-axis surface grooves are formed in the portion, at the position of each magnetic steel sheet, of the surface of the iron core of the rotor. Every two d-axis surface grooves corresponding to the same magnetic steel sheet are symmetrically distributed on the two sides of the center line of the magnetic steel sheet. The distance between the axes of every two d-axis surface grooves corresponding to the same magnetic steel sheet is approximate to the width of the tooth end of a stator tooth of the permanent magnet synchronous motor. The invention further discloses the rotor of the permanent magnet synchronous motor. According to the permanent magnet synchronous motor and the rotor of the permanent magnet synchronous motor, torque fluctuation in a low-torque area can be reduced; in addition, the structure is simple, machining and manufacturing are easy, and cost is low.