Discharge and ablation between the rails and the armature with hypervelocity remains a main obstacle in the field of electromagnetic rail launching. The structure of a simple rail launcher was introduced and its mechanics of discharge and ablation was analyzed. The reason is that the concentrated current in the back corner of the rails-armature structure leads to too much Ohmic heat. On considering the melting and erosion, we suggest a method that the structure of rail launcher could be modified to solve the problem of ablation. The proposal is about a multi-layer of rail-armature structure. The results of finite element analysis revealed that the new structure launcher is feasible and effective to control the ablation.