Abstract: In order to analyze the influence of the dynamic characteristics of the sliding sleeve and the engagement ring gear on the shifting process in the two-speed automatic mechanical transmission system (AMT) without a synchronizer, a position angle of the sliding sleeve was defined to determine the specific collision between the sliding sleeve and the ring gear.Firstly, a nonlinear dynamic model of the sliding sleeve and the ring gear was established.Then, considering the non-linear factors such as meshing stiffness, meshing damping, tooth side clearance, and static error, a dynamic model of the gear shifting process was established.Comparing with the synchronizer model in simulation analysis, the advantages of the synchronizer-less AMT system were embodied.Finally, the simulation was carried out to analyze the influence of different magnitudes of axial thrust on the shifting process.The results show that 150N axial thrust is more appropriate.This analysis method can be taken as a reference for selecting the appropriate axial thrust and the application of the AMT system in engineering.