Abstract: According to the status of rotorcraft and mechanical structure of three-rotor, this paper analyzed the torque of a three-rotor aircraft and established its mathematical model. Active disturbance rejection control (ADRC) was applied to the control of attitude. To investigate the performance between ADRC and PID, series of comparative experiments were carried out. Results show that different sizes of step signal can be adjusted by different parameters in ADRC, and ADRC is more effective and rapid than PID. ADRC can not only keep the general framework and structure of PID, but also has better performance on filtering and robustness, which has important guiding significance in engineering and experiments.