Abstract: Aiming at the difficulty of detecting early fretting wear on railway axle press fitting interface, an ultrasonic detection and analysis model of axle press fitting interface containing fretting wear was established based on the Comsol solid mechanics and elastic wave physical field coupling module. The ultrasonic guided wave nonlinear coefficient and ultrasonic transmission coefficient were constructed with the amplitude of transmitted signal base wave and second harmonic wave as the characteristic values. The effects of the wear depth, length and force on the nonlinear coefficient and transmission coefficient of ultrasonic guided wave were discussed, and the fretting wear dimension evaluation model of axle pressing interface was proposed. The results show that the nonlinear coefficient increases with the increase of wear depth and length, and decreases with the increase of pressing force. The ultrasonic transmission coefficient decreases with the increase of wear depth and length, and increases with the increase of pressing force. This will provide a theoretical reference for the dimensional quantitative evaluation of fretting wear on the axle press mounting interface.