Abstract: Equations with 6-degree-of-freedom motion were used to study the effect of air turbulence on vertical overload of an airplane.The transfer function of overload as the airplane flying in turbulence was deduced,and the airplane response to non-stationary air turbulence was analyzed.The results show that,at a subsonic speed,airplane turbulence increases with an increase in flying speed,and that a smaller airplane is affected more fiercely than a bigger one under the same air turbulence and weather condition.