Based on the status of rotorcraft research at home and abroad,a kind of trirotor aircraft with a tiltable tail rotor is studied.Firstly,the mechanical structure of the trirotor aircraft is introduced,the forces and overall torque of the aircraft are analyzed,and the mathematical model of the aircraft is established by using Newton-Euler equation.Then,in view of the fact that the system is highly nonlinear with strong coupling,and is easily be affected by disturbances,the Active Disturbance Rejection Control(ADRC) is used to control the system.Finally,a flight control simulation and a disturbance rejection test are conducted based on Matlab/Simulink,and then the controller is compared with PID controller for further analysis.Simulation results show that,compared with PID controller,ADRC can realize a more rapid and stable adjustment to the attitude and height with stronger anti-disturbance ability.