Electromagnetic rail launch has typical ultra-high-speed sliding electrical contact characteristics (launch speed is greater than 2 000 m/s),and the rail surface will be worn.To investigate the correlation between track surface status and contact resistance,electromagnetic rail launch experiments were conducted to investigate the formation and wear mechanism of CuCrZr rail surface deposition layers after launch.The evolution law of static contact resistance between armature and rail was revealed,and the correlation between deposition layer formation and contact resistance was summarized.The results show that along the launch direction,the coverage area of the deposition layers on the rail surface gradually increases,and the formation mechanism of the deposition layers changes from friction material transfer to melting and spattering of the armature surface,and the surface wear characteristics change from mechanical wear to electrical wear.Due to the different reasons for the formation of deposition layers at different regions of the rail,the distribution of surface roughness is inconsistent,and the static contact resistance between armature/rail shows three stages of increase,decrease,and fluctuation as the contact deposition layers morphology changes.The static contact resistance between armature/rail decreases as the contact pressure increases.The research results have theoretical value for the study of electromagnetic rail launch equipment and launch dynamics.