Ultra-high-speed permanent magnet synchronous motor (PMSM) has the characteristics of high speed and low radial force wave orders, but its stator is easy to resonate and cause loud noise. Taking an ultra-high-speed PMSM as an example, the electromagnetic field model of the motor and the 3D modal model of the stator structure are established based on the actual size of the motor. The radial electromagnetic force of the motor is simulated by finite element method, and the main harmonic frequencies of the electromagnetic force causing the vibration of the motor are analyzed, through which the main source of electromagnetic noise is confirmed. Finally, the electromagnetic noise characteristics of ultra-high-speed PMSM are studied by using the sound pressure level cloud image of ANSYS.