Abstract: An anti-off switch for an air-conditioning vent includes a frame, a panel rotatably connected to the frame, and a switch installed between the frame and the panel for opening or closing the panel. The frame includes a strip plate protruded from a side of the frame, and a corresponding latch plate rotatably coupled to a side of the panel, and the latch plate includes a wrench portion exposed from an external surface of the panel, and a connecting portion disposed between a side of the panel and a side of the frame, and the connecting portion includes a hook for latching the strip plate. The switch allows users to open and close in a normal operation for use, while providing a self-locking function for unauthorized use, so as to prevent the switch from being opened by unauthorized persons and provide a good security of use.