The invention discloses an ascending overspeed protection triggering device of an elevator. The device comprises a plate-type switch and a rocker arm limit switch matched with the plate-type switch, wherein the plate-type switch is in a vertical state and an electrical circuit is communicated; the plate-type switch is installed on a speed limiter framework and rotates on the speed limiter framework; after the plate-type switch rotates, the electrical circuit is disconnected, the plate-type switch is located above a centrifugal hammer in a speed limiter, and the plate-type switch is driven to rotate through the centrifugal movement of the centrifugal hammer in the speed limiter; the plate-type switch is provided with the rocker arm limit switch, the plate-type switch rotates to squeeze therocker arm limit switch, and accordingly a contact of the rocker arm limit switch is squeezed to move. Compared with the prior art, the ascending overspeed protection trigger device has the advantagesthat at the overspeed, the speed limiter drives the plate-type switch to rotate in different directions, an oblique boss structure on the plate-type switch is ingenuously utilized to be in contact with the rocker arm limit switch, and therefore the function of the unidirectional movement of the bevel-angle rocker arm limit switch when the rotation directions of the plate-type switch are differentis achieved.