Abstract: ［Objective］ Metro wheel polygonal wear causes vehicle vibration, affecting the smoothness and comfort of the vehicle operation. The existing static detection methods for wheel out-of-roundness consume a lot of manpower and mat-erial resources, a dynamically monitoring for the wheel polygonal wear severity is required. ［Method］ A dynamic simulation model of whole-vehicle rigidity and sub-rail foundation flexibility is established; a wheel polygonal order characteristic analysis method based on rail vibration acceleration is proposed; the wheel polygonal wear evaluation index is analyzed and verified based on measured data. ［Result & Conclusion］ The wheel polygonal degree index K is less affected by track irregularity and can quantitatively reflect the degree of wheel out-of-roundness; the wheel polygonal amplitude calculated based on the evaluation index K has better consistency with the actual wheel circumferential radial runout amplitude.