Air canard was controlled by servo mechanism when traditional tactical missile was flying in atmosphere. However, it cannot meet the requirement of the low cost and small missile body applications. This paper proposed a new method of guided mortar control, which makes use of the aerodynamic force as the power resource of the power mechanism. Control force was generated by controlling differential rotation rate between missile body and the canard which drives the missile hit the target. The differential rotation rate control without traditional servo mechanism was operated only by the permanent magnet motor which was installed between the warhead and the missile body. The method decreased the cost and the volume of control system, and had very satisfactory cost-effectiveness ratio.