In order to investigate the effects of different rotor topologies on the electromagnetic and noise performance of 8-pole 48-slot interior permanent magnet synchronous motor (IPMSM), finite element models of interior permanent magnet synchronous motors with single-layer non magnetic bridge, singlelayer magnetic bridge, double-layer non magnetic bridge, and double-layer magnetic bridge rotor topologies are established. Except for the rotor topology, the stator topology, permanent magnet usage, and other conditions of the four types of motors are completely the same. Firstly, the electromagnetic performance and noise performance of the motor are analyzed theoretically. Secondly, the finite element models of four kinds of motors are established, and the electromagnetic performances of the four kinds of motors, such as salient pole rate, output torque, torque ripple and no-load back EMF harmonic distortion rate are compared and analyzed, and the modal analysis of the four kinds of motors is carried out. Finally, the vibration response and noise characteristics of the four kinds of motors are compared. The results show that the interior permanent magnet synchronous motor with a double-layer rotor structure with a magnetic isolation bridge has the best electromagnetic performance, and its noise reduction effect is also the best.