Drag-reduction and fuel conservation, one of the significant benefits of active center of gravity (CG) Control function, plays an important role in iterative and optimal design of function scheme. Based on its principle and scheme, the active CG control function of a certain aircraft was modelled，coupling with flight control system model, automatic flight control system model, fuel system model, aerodynamic model，engine model and aircraft 6-DOF model, with the consideration of effect of CG variations induced by fuel consumption. At the given altitude and Mach number, the benefits of active CG control function were estimated, through setting different target CG positions. The results show that it can bring considerable benefits to aircraft with the application of active CG control technology, especially the more backward the target CG is, the more obvious benefits will be generated. The Mach number has an impact on the benefits of the function. Under the same conditions, the larger the Mach number is, the greater the return will be.