An action reciprocating structure of a toy gun an action part and a gear box of a loading mechanism, of a toy gun, wherein the action part is located at a top of the toy gun, the gear box is located at a bottom of the toy gun, and a reciprocating mechanism is located between the action part and the gear box. The reciprocating mechanism includes a pump mechanism, connected to a reciprocator which is provided with an elastic member and a small piston having an air-tight ring therein. When the pump mechanism is filled with gas to push an air-tight piston in the pump mechanism, it also pushes the elastic member and the small piston of the reciprocator, such that the action part which is connected on the small piston can achieve an emulated shooting effect of a reciprocate movement, at the same time.