The invention provides a remote high-pressure well opening emergency cut-off device. A pressure reducing valve is fixedly connected to one side of a valve body of an emergency cut-off valve in a sealed mode. The pressure reducing valve comprises the pressure reducing valve body, a pressure reducing valve deck and a pressure reducing valve element. A pressure gas inlet hole and a pressure gas outlet hole in the pressure reducing valve body are communicated with a gas inlet channel and a gas outlet channel respectively. The pressure reducing valve element is arranged in the pressure reducing valve deck. A pressure reducing valve main spring is arranged between the pressure reducing valve element and the pressure reducing valve deck. The lower end of the pressure reducing valve element is provided with a pressure reducing valve main sealing ring. The pressure reducing valve main sealing ring is provided with a conical sealing surface and is made of corrosion-resistant materials. The pressure reducing valve main spring is a mold spring. The surface of the pressure reducing valve main spring is subjected to electrophoretic treatment. By adopting the remote high-pressure well opening emergency cut-off device, a pressure pipeline can be opened more safely and smoothly, the circulation path size of a pressure reducing insert bush can be selected according to different working conditions, and various requirements of different well sites can be met. The pressure reducing valve main sealing ring is resistant to corrosion and good in sealing stability, and the pressure reducing valve main spring is stable and reliable.