To the effects of varying mass of tanker and receiver in aerial refueling, the dynamic equations of aircraft are derived and the simulation is done when the fuel is transferring. By treating the varying mass as disturbance forces and moments to such aircraft, the dynamical equations of translational and rotational motion of mass-varying aircraft are derived. After simplifying the model according to the practical situation, the linear small perturbation model with varying mass disturbance in the longitudinal channel is derived. The computer Simulation of examples of tanker and receiver in aerial refueling show that the effect on tanker is small, however the pitch angle, airspeed, altitude of receiver changes acutely.