Abstract: This paper carries out the simulation of the multi-physical coupling field between the armature and the guide rails in high-speed movement during the electromagnetic emission, by using a marching-on-in-time (MOT) coupling algorithm to construct the multi-physical field coupling structure, to study the transient coupling process of the electromagnetic, thermal and mechanical fields by a finite element simulator we have developed based on the electromagnetic analysis and the thermal conduction laws. Taking a typical track electromagnetic gun as an example and with a single pulsed large current as the excitation power, the distributions of the time-based variables such as the current density, the magnetic induction, the Joule heat and the electromagnetic force are simulated dynamically. The calculated results can directly reflect the physical phenomena such as the velocity skin effect, and meanwhile, it is easy to obtain the transient data of the multiple physical fields with spatial and temporal variations during the electromagnetic emission process. The results of this paper can be used for the design, optimization, and evaluation of electromagnetic transmitters.