The effect of tropical cyclone horizontal scale on its motion is investigated in a nondivergent, barotropic model with no basic flow. The tropical cyclone whose horizontal scale is smaller (larger) moves toward the northwest by north (the northwest by west). The asymmetric flow of the smaller (larger) tropical cyclone causes the large scale beta gyres to countercloockwise rotate a smaller (larger) angle αl. The moving direction of tropical cyclone θc is related to the angle αl,i.e., θc≈360°-αl. Therefore, the moving direction of tropical cyclone counterclockwise deflects to the west with the increasing of horizontal scale.