A toy gun comprising a bullet chamber, a gas bottle container, a regulation valve, a regulation chamber and a control valve in a magazine shell, at least one partitioner is installed inside the regulation chamber, the partitioner subdivides the regulation chamber into several small chambers in series, several small holes are on the partitioner to interlink these small chambers, the small holes are made in conical shape with smaller diameter toward first chamber side. In real application, the gas flows from the gas bottle to the first chamber then to next chambers through those small holes, the gas entering the first chamber cannot flow into the next chamber completely as the gas flow reservation and buffering effect, the gas pressure variation is minimized at the regulation valve close moment and offer a stable, safe shooting power source.