The performance of permanent magnet synchronous motor (PMSM) is excellent. However, the permanent magnet excitation cannot be regulated, which leads to a limited speed regulation range. A novel rotor structure of negative-salient permanent magnet synchronous motor (NSPMSM) is proposed by utilizing the magnetic bridge to increase d-axis inductance and the W-shaped permanent magnet to decrease q-axis inductance. The characteristics of torque and flux-weakening speed regulation of the NSPMSM are analyzed by theoretical analysis, and the negative-salient polarity is verified by the finite element method. The influences of rotor structure parameters on the electromagnetic torque and speed regulation performance of the NSPMSM are studied. The flux-weakening simulation results obtained by finite element method are consistent with the theoretical analysis results, which verifies the effectiveness of the structure in improving the flux-weakening speed regulation range.