Abstract: The roll axis control power of low-aspect-ratio flying wings were assessed based on the criteria for Class Ⅳ aircraft presented in MIL-STD-1797A. The relationship of the roll performance requirement and the roll axis control power requirement was provided. Low-aspect-ratio flying wings need more roll axis control power with the same roll performance requirement, because of the all-wing configuration and the lager rolling moment of inertia. Without the vertical tail's contribution, the static lateral stability and control side force of the flying wing are less than those of the conventional combat aircraft, and with the application of innovative control effectors and the control allocation technology, low-aspect-ratio flying wings can achieve the decoupling control. As a result, the roll axis control power requirements of the flying wing for takeoff and landing in crosswinds and for asymmetric loading, have a lot of new characteristics in contrast with those of the conventional-configuration aircraft.