The repulsive forces exist between the two rails when the armature is thrusted forward along the rail. At the same time the armature expands due to Joule heat, which causes rail’s vibration.The electromagnetic rail was modeled as a simply supported beam of finite length sitting on an elastic foundation. According to the theory of vibration, the dynamic response of the rail was governed by a fourthorder differential equation with an extra term of elastic support subjected to armature’s thrust. Then the parameters, such as the current intensity, the elastic constant and damping of the elastic foundation, were analyzed. The theoretical basis of the design of rail was obtained from the analysis result.