A spraying gun includes a gun body, a control valve, and a nozzle head. The control valve includes a valve body, an adjusting switch, a rotation knob, and a container. Thus, the water from the gun body is injected through the inlet flush hole of the valve body and the inlet flush bore of the adjusting switch into the receiving space of the container to stir and mix with the detergent, and the water and detergent mixture is injected through the outlet injection bore of the adjusting switch and the outlet injection hole of the valve body into the nozzle head, so that the water is mixed with the detergent in the container exactly and completely, thereby enhancing the washing effect of the spraying gun.