Abstract: A reverse-salient permanent magnet synchronous motor has a direct-axis inductance larger than quadrature-axis inductance, and possesses the advantages of wide constant-power speed range, strong overload capability and low demagnetization risk of permanent magnets, which is suitable for electric drive systems and other occasions with high speed regulation requirements. Due to the different directions of the main magnetic field, radial-flux and axial-flux reverse-salient permanent magnet synchronous motors show significant differences in topological structures and electromagnetic performances. Firstly, two topological structures of reverse-salient permanent magnet synchronous motors are proposed, namely radial flux and axial flux. Corresponding equivalent magnetic circuits in the AC and DC axes are established respectively, and the magnetic field regulation mechanism is analyzed. Secondly, the electromagnetic performances of the two motors, such as torque density, torque ripple, constant-power speed range and efficiency, are compared and studied based on the finite element method. The results show that the radial-flux reverse-salient permanent magnet synchronous motor performs better in torque ripple and constant-power speed range, while the axial-flux reverse-salient permanent magnet synchronous motor has certain advantages in torque density and efficiency. Finally, a prototype of radial-flux reverse-salient permanent magnet synchronous motor is developed, and the accuracy of the finite element analysis results is verified by experiments. The performance research on the two motors clarifies the differences in electromagnetic characteristics and applicable scenarios of different types of reverse-salient permanent magnet synchronous motors, which provides a theoretical basis for their engineering applications.