The invention discloses an outer wing folding mechanism of an aircraft, which comprises a fixed wing, one side of the fixed wing is connected with a folding wing through a hinge support mechanism, and a folding power mechanism is arranged between the fixed wing and the folding wing , the folding power mechanism includes a servo motor, a screw rod, a folding shaft and a sleeve, the servo motor is fixedly installed on the spar of the fixed wing through a motor base, and the output shaft of the servo motor is connected to the screw rod through a joint The screw nut adapter is sleeved on the screw rod, the screw nut adapter is fixedly connected with a folding shaft, the inner wall of the sleeve is provided with a spiral groove, and the folding shaft The shaft is arranged in the sleeve, and the expansion shaft is engaged with the spiral groove. The sleeve is fixedly connected to the spar of the folding wing, and has a relatively large transmission ratio, which increases during the wing folding process. The output torque is increased, the wings can be easily unfolded, and it has the ability of one-way self-locking.