The invention provides an aircraft cabin door lock mechanism. The aircraft cabin door lock mechanism comprises a first end cover, an acting cylinder, a second end cover, a piston rod, a lock hook and a spring. According to the aircraft cabin door lock mechanism, the lock hook is hinged on the acting cylinder; one end of the lock hook is connected with the piston rod in the acting cylinder and the other end of the lock hook is hung on a cabin door lock ring; when the acting cylinder inflates to move a piston so that the lock hook can be driven to move and a cabin door is unlocked; and when gas in the acting cylinder is exhausted, the lock hook is driven by the piston to move so that the cabin door is locked. By adopting the structure, a locking principle of a traditional lock structure is simplified and the volume of the lock structure is reduced; and the aircraft cabin door lock mechanism is suitable for a small-size aircraft with high requirements on a small-layout space.