The invention relates to a method for autonomous flight of a four-rotor unmanned aircraft by using an auto-disturbance-rejection control technique, belonging to the
automatic control field of unmanned aircraft. The method comprises the steps of: respectively making differences between an output xld after arranging a transient process of a target value and an output of an extended
state observer, and differential of the output xld and the output of the extended
state observer respectively, and then carrying out nonlinear conversion on two differences to obtain a nonlinear
feedback control law u0; with regard to an auto-disturbance-rejection controller with three attitude angles and
vertical displacement, making difference with feedback of the extended
state observer to obtain an output as an input of a corresponding channel of a four-rotor
system and the extended state observer; and with regard to an auto-disturbance-rejection controller with forward and side displacements, directly using u0 as the input of the corresponding channel of the four-rotor
system and the extended state observer, and feeding back the actual value to the extended state observer after the corresponding channel of the four-rotor
system responses, so as to form an close-loop auto-disturbance-rejection controller. The method is strong in capacity of resisting disturbance, and the problems of difficulty in modeling of the four-rotor system, environmental diversity in the
flight process, and frequent interferences are effectively solved.