In the ultra-high speed stage of the electromagnetic launch, there is impact with a small incident angle between the armature and rail (A/R), which is caused by severe melting wear of the armature tail and stress wave transmission of the rail. In this article, the model of armature/rail impact is established. Simulations are carried out with different A/R structures by using ABAQUS/EXPLICIT. The results show that the armature tail experiences considerable deformation and bouncing vibration behavior during impact collision, resulting in dynamic change in the contact area of A/R interface. The flat A/R interface loses contact under impact, suggesting that the transition occurs. In contrast, the concave A/R interface remains in contact and the contact area changes in stability. Moreover, a larger central angle leads to a smoother trend of contact area change. It can be concluded that under the high-speed armature/rail impact, the concave armature with a lager central angle has a better contact with rail result in suppression of the transition.