Compared with conventional configuration aircraft, tailless flying wing configuration aircraft has a longer wing span than chord length. Aircraft with such aerodynamic characteristic has a shorter pitch arm and its pitch trim ability is insufficient when climbing at low speed and high angle of attack. Therefore, further exploring the aerodynamic efficiency of aircraft control surface and improving the pitch trim ability become a problem to be studied. The flying wing aircraft mostly adopts the split resistance rudder (SDR) symmetrical deflection to realize the stable control of the aircraft course; such an approach is simple and effective, but it reduces the control efficiency of the surface. So we want to explore the SDR asymmetric deflection control scheme to enhance the pitch control capability of the aircraft. In this paper, the dynamic modeling of SDR asymmetric deflection is studied and the mathematical model of over-drive system is established. The control effectiveness of SDR asymmetric deflection and symmetric deflection is compared by solving its attainable moment subset. The simulation results show that: Compared with symmetrical deflection, the pitch moment of asymmetric deflection control scheme increased by 47.5%. It can achieve greater pitch trim ability and control ability.