Research on Hyper Tube, a Korean high-speed HTS Maglev train, has reached the verification stage for actual operation, and electromagnetic dynamic characteristics analysis of the train is required accordingly. Depending on the winding type of the propulsion armature, the HTS magnet experiences the harmonic that causes AC loss. Beside the static thermal losses by thermal conduction, current leads et al., the AC loss should be take account for the thermal battery design depending on operation conditions. This study describes the AC loss analysis of the HTS magnet induced by the harmonic using the homogeneous <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T-A</i> formulation widely used in recent. In consideration of acceleration and cruise conditions, the effect of the AC loss by harmonics on the capacity of the solid nitrogen thermal battery was discussed.