The invention discloses a steel-made welding pressure difference control valve. The steel-made welding pressure difference control valve is characterized in that a film box is buckled to the top of a film box base; a valve base is arranged in a valve body; a cone valve clack is arranged in the valve body, and a valve plug is arranged in the film box base and the film box. Two connecting tubes are respectively welded on both sides of the valve body; the valve base in the valve body is respectively connected with said two connecting tubes; the top of the valve body is provided with a circular hole and welded with a connecting sleeve, the film box base and the connecting sleeve are fixed to the valve body; the top of the valve base and the bottom are respectively provided with a valve port relative to the circular hole on the valve body, said two cone valve clacks are respectively plugged in said two valve ports to play an adjustment role; the film box is divided into a film top cavity and a film bottom cavity by films in the film box, the film top cavity is connected with said two connecting tubes through pressure guide holes on the film box via a pressure regulating valve, and a pressure guide tube. The control valve is low in resistance, appropriate to heat preservation, and connected with a pipeline by a welding connection manner, so that a pipeline net is more safe and steady, and longer in service life, the construction cost and the leakage point of the pipeline connection are reduced. The control valve is made of a steel tube, thus atmospheric contamination caused by the casting process in manufacturing processes of the primary pressure difference control valve is changed.