Abstract: Based on solid heat conduction theory and multi-physics field coupling theory, the calculation equation of the armature surface transient wear is deduced, and the calculation method of contact resistance and the transient contact force is proposed. On this basis, armature transient wear calculation method is summarized and presented. The armature transient wear is analyzed with this method, when the contact length and width are changed. Pivot rail contact surface of wear is mainly distributed in the front edge and on both sides of the edge. Along the length direction of the contact, the wear is more and more light; along the contact width direction, the wear quantity increases firstly and then decreases; the middle part wear is light. Finally, armature surface wear rate calculation results are compared with the experimental results of IAT and they are in good agreement. This lays a foundation to establish relationship between armature wear and the transition theory.