In order to study the influence of rail weld short wave irregularity on the dynamic response of metro vehicle wheel/rail, a kind of expression of weld short wave was proposed based on Gaussian function. Based on the vehicle track coupling dynamics theory and the simulation analysis software universal mechanics (UM), the influence of new models and traditional harmonic models on the dynamic characteristics of metro vehicle wheel/rail was studied, and the influence of weld short wave wavelength and wave depth on the dynamic response of wheel/rail was analyzed, On this basis, a safety threshold for short wave roughness of subway welding seams was proposed. The analysis results indicate that compared with the traditional harmonic model, the new model exhibits a "lean high" characteristic, with measured irregularities between the two types of models, and the slope of the local area is closer to the new model. When the vehicle passes through the weld zone at high speed, the new model causes greater high frequency transient impact force on wheel/rail (P₁), wheel load reduction rate, rail acceleration, and axle box acceleration than the traditional harmonic model. The wheel load reduction rate caused by the two types of weld models increases Exponential type with the deepening of wave depth, and decreases inversely with the increase of wavelength. Using the wheel load reduction rate as the evaluation criterion is more stringent than using the wheel rail vertical force. When the wavelength is small, the difference is not significant, while when the wavelength is large, the wave depth obtained by using the wheel rail vertical force as the evaluation criterion is twice the wheel load reduction rate. Compared with traditional harmonic models, the new model calculates wave depths more strictly.