Abstract: Wheel polygonal wear can lead to abnormal vibrations and noise during train operations, causes component fractures, and seriously affects both running comfort and safety. The operation of a train with changing running speed is a potential suppression measure for polygonal wear development, however this method has not been studied deeply and effectively. Using a wheel-rail twin disc rolling test rig, the development process of wheel polygonal wear under the conditions of constant speed and oscillating speed is reproduced, and the trend of polygonal wear development under oscillating speed running is studied. Test results show that the resonance of the natural frequency of the wheel-rail system in the test rig is the main reason for polygonal wear generation and development, following a wavelength-fixing mechanism. In the oscillating speed running, if the passing frequency caused by the polygonal wavelength is consistent with the natural frequency of the system, the wheel polygonal wear of this wavelength would develop. Otherwise, it would be suppressed. Under oscillating speed running conditions, even by adopting a higher operating speed than in uniform speed conditions, it is still possible to achieve a lower rate of polygonal wear development than in uniform speed conditions. Under constant speed and oscillating speed conditions, the maximum value and stable value of polygonal wear depth are basically the same. However, compared with the constant speed condition, the mileage at which the maximum value and stability of wave depth appear under the oscillating speed condition is postponed by 50% and 40%.