To solve the problem of parameter perturbation and uncertainty in the flying process of fixed-wing UAV formation, a robust control method for the leader-follower UAV formation based on adaptive disturbance observer is designed.The leader-follower UAV formation model and the UAV motion model are established, and the properties of the adaptive law of discontinuous projection are demonstrated.Then, the robust control law for the inner loop is designed to track the command signal produced by the outer-loop formation controller.In the design process of the robust control law, the adaptive law for the parameters is introduced to online estimate the parameter perturbation, the adaptive disturbance observer is designed to observe and compensate for the uncertainties, and the stability analysis is given by using the Lyapunov function.Finally, simulation results demonstrate the effectiveness of the proposed method in the robust control of UAV formations.