In this paper, a design method for a wound field synchronous motor (WFSM) employing the dual stator winding and the winding connection change circuit is proposed. Through the design method, the WFSM can be operated as two different modes, and each mode is determined by the connection between the stator windings U, V, W and X, Y, Z. By applying the proposed method to the conventional WFSM, the operation mode of the motor is changed at a certain speed. The speed for the mode change is determined to maximize the efficiency of the machine. As a result, through the mode change, the line to line induced voltage, current phase angle, and phase resistance are decreased. In addition, the demand field current is also reduced to achieve the required torque due to the salient pole characteristics of WFSM. Consequently, the efficiency of the WFSM is increased due to the mode change. Finally, the effect of the proposed method and the validity of the simulation results are verified by the load test.