Abstract: A sine-wave current line-start three-phase rare-earth permanent magnet synchronous motor includes a motor shaft, a rotor and a stator. The rotor is disposed inside the stator and rotates around the motor shaft. The rotor includes P pairs of poles. Each pole includes a polar arched surface. A planar surface is formed between adjacent polar arched surfaces. Thus, a non-uniform air gap is formed between the pole face of the rotor and the inner circumferential surface of the stator. By the use of a salient-pole structure with the non-uniform air gap, the asymmetry of the magnetic circuit caused by permanent magnets can be offset, thereby making the manufacturing process of the rotor simplified, the negative sequence components of the rotor current during the line starting process reduced significantly, the starting performance improved, the sine-wave current provided during the operating process, the harmonic loss reduced, and the motor efficiency enhanced.