A nail gun structure includes a gun body, a clamp set and a pneumatic driving set. The gun body has a trigger for shooting a nail. The clamp set is assembled with the gun body. The clamp set has a driven base and a clamp base. The clamp base pivots relative to the driven base. A stacked board is positioned on the clamp base. The pneumatic driving set is disposed between the gun body and the clamp set. The pneumatic driving set communicates with an air pressure source. The trigger moves along with the pneumatic driving set. Under this arrangement, when a user pulls the trigger, the pneumatic driving set drives the clamp base to pivot, so that the stacked boards are clamped between the clamp base and the driven base; thereafter, the nail is shot and nailed on the stacked board.