Aiming at a special rail corrugation phenomenon near the point of tangent to spiral of metro line,a numerical model of vehicle-track system was established according to the field conditions,and the validity of the model was verified.The stick-slip characteristics of wheel-rail interface were analyzed by the numerical model,and the cause of rail corrugation was explained.Combined with the dynamic response characteristics of wheel-rail system,the establishment condition of the fixed-wavelength attribute that promoted the generation and development of rail corrugation was investigated.The results show that,in the interval near the point of tangent to spiral of the line,lateral stick-slip motion will occur at the inside and outside wheel-rail interfaces of guiding wheelset and driven wheelset,while the probability of longitudinal stick-slip motion at the wheel-rail interfaces is low,and the alternate occurrence of stick-slip motion leads to the formation of initial corrugation on the rail surface.When the inner and outer wheels of guiding wheelset and driven wheelset pass through the line point of tangent to spiral,the outside wheel-rail contact is characterized by the wheel flange-rail gauge angle contact,and the variation of contact type causes the fluctuation of normal force of wheel-rail system,which shows that the existence of the point of tangent to spiral gives the phase synchronization characteristic of wheel-rail lateral stick- slip motion,and can maintain the fixed-wavelength attribute of rail corrugation.Therefore,the rail corrugation is finally formed and continuously developed,and the inner rail is characterized by rail surface corrugation and the outer rail is characterized by side corrugation,which are consistent with the corrugation phenomena in the measured interval.