Abstract: Under the assumption that the guide rail is a semi-infinite solid conductor and main armature surface wear is the wear based on melting, and according to the solid contact heat conduction principle, the armature and the rail temperature distribution equations are deduced, and the calculation method of average wear rate in armatures is put forward. The influences of average wear rate on driving current, the matching of armature and guide materials and the contact area of the armature are studied. The average wear rate calculation results agree well with Stefani and Parkers experimental results, which verifies the validity of the method.