Abstract: A discrete-time sliding mode（DTSM）control method based on a discrete-time disturbance observer (DTDO) and the neural network（NN）is proposed for a fixed-wing unmanned aerial vehicle（UAV）system with external disturbances and system uncertainties. The DTDO is used to suppress the adverse effects of external disturbances on the control performance of the system, and the system uncertainties are approximated by the NN. The DTSM controller is further designed by combining the saturation function, the discreteform tracking differentiator and the backstepping control technology, and the stability of the closed-loop system is proved with Lyapunov stability theory. Finally, the numerical simulation results of the UAV system under the gust illustrates the effectiveness of the attitude control scheme.