The invention provides a clamping mechanism of a card discharging machine. The clamping mechanism is arranged on a card output channel of the card discharging machine. The clamping mechanism comprises a card clamping device, and an upper rack plate and a lower rack plate which are arranged on the two ends of the card clamping device. A card clamping motor is arranged on the upper rack plate and a linkage rope is tied to the lower rack plate. The other end of the linkage rope is connected with the card clamping motor. A resetting spring is arranged between the upper rack plate and the lower rack plate. The clamping mechanism can clamp cards in a card discharging machine and move the cards stably and safely in the direction close to vehicles, so that the cards are closer to the vehicles.