In view of the expensive and time-consuming shortcomings of traditional gain scheduling technology in many UAV applications,through the six-degree-of-freedom nonlinear model of a fixed-wing UAV,under the condition of known the aerodynamic coefficient,aircraft moment of inertia and thrust coefficient,the linear parameter varying (LPV) aircraft model is derived from the six-degree-of-freedom nonlinear model by using Jacobian linearization method.The tensor-product (TP) model transformation method is used to transform the longitudinal nonlinear parameter-dependent LPV model of UAV into TP convex polyhedron model.The robust H_∞ controller design method of gain scheduling output feedback is applied to the TP convex polyhedron model,and the robust gain predictive autopilot flight control system of conventional fixed-wing UAV is designed.A full six-degree-of-freedom aircraft simulation test of the control system is carried out in MATLAB SIMULINK environment.The results show that the closed-loop control system has good command followed,interference suppression ability,good stability and robustness in the given flight envelope,which verifies the effectiveness of the proposed flight control system.