Abstract: The contact model and collision model of hemisphere asperity pair were established by finite element method, and the influence of asperity collision on Mises stress and equivalent plastic strain (PEEQ) were analyzed taking into account fully elastic contact, elastoplastic contact and fully plastic contact. The numerical results show that the changing processes of Mises stress distributions in the asperities depended on contact status. The Mises stress decreased and was no longer greater than yield limit after the collision in addition to several nodes in the fully plastic contact status. The PEEQ of the asperities increased rapidly to their maximum and were constant till the end of the collision regardless of the contact status of the asperities. The maximum of PEEQ of the asperities were in different location, and this result implies there were different locations of crack initiation in different contact status.