The invention provides a dual-redundancy electric throttle mechanism for an automatic control system. The dual-redundancy electric throttle mechanism comprises a shell and a mounting seat, wherein the shell comprises an upper shell, a main shell and a lower shell; the shell and the mounting seat are in damping flexible connection through a three-point shock absorber; a dual-redundancy motor and a clutch are arranged in the shell; an output shaft of the dual-redundancy motor is provided with a gear I and a gear II; the gear I and the gear II are connected with a rear gear ring and a front gear ring on the clutch through a gear bank I and a gear bank II; the rear gear ring and the front gear ring are fastened to a rear fluted disc and a front fluted disc of the clutch separately; and a movable fluted disc on the clutch is connected with an output shaft of a harmonic reducer and the movable fluted disc is arranged between the rear fluted disc and the front fluted disc. The dual-redundancy electric throttle mechanism is small in volume, light in weight, high-temperature resistant, high in vibration resistance and high in precision, and is more suitable for an unmanned aerial vehicle.