In order to study the cause of rail corrugation in the straight starting section near the metro exit， the transient rolling contact model of three-dimensional solid wheelset-track is established by using the finite element software ABAQUS， and the corrugation phenomenon is analyzed in time-domain and frequency-domain based on the field measurement. The results show that， during the starting of the vehicle， the quasi-periodic sliding zone can be produced in the contact surface between wheel and rail， and the distance between the centers of sliding zones is close to the wavelength range of the measured corrugation， which verifies the rationality and effectiveness of the model. The unstable friction self-excited vibration of wheelset-track system is the fundamental cause of rail corrugation in the measured section， and it is precisely because of the "saturated-unsaturated" periodic characteristic of wheel-rail creep force that ultimately promotes the formation of rail corrugation. The vertical vibration acceleration levels of rail and wheel have a peak area in the frequency range of 160~230 Hz， and the frequency range is close to the characteristic frequency range of 174~198 Hz of the measured corrugation， which further indicates that the rail corrugation is caused by the wheel-rail resonance from the friction self-excited vibration of wheelset-track system. On the premise of ignoring the initial irregularity， the corrugation on rail surface shows a linear growth trend with the increase of wheel operation times. Therefore， it is very important to take appropriate measures such as rail grinding and rail surface lubrication.