<p>The hunting motion of vehicle system is a crucial nonlinear motion but its bifurcation and nonlinear characteristics under lateral track irregularities remain insufficiently explored. This study proposes an analytical solution method to analyze the characteristics of hunting motion under lateral track irregularities. The results show that there is a spatial coherence between the lateral track irregularity wavelength and the bogie system axial distance, which affects the proportion of the same-direction and reverse-direction hunting motion modes of the front and rear wheelsets. There is a bifurcation of forced motion under track irregularity. The amplitude and wavelength of the track irregularity affect the bifurcation behavior of the forced motion, but with different mechanisms. Furthermore, lateral track irregularities can alter the bifurcation velocity and bifurcation type of system’s self-excited motion by constricting the attraction domain of the zero solution and modifying the phase-space trajectory.</p>