The invention discloses a pressure differential contact point moving system, which belongs to the technical field of mechanical design. The pressure differential contact point moving system comprises an air inlet valve, an exhaust valve, an air compressor, a turbine, a lever, a tappet rod, a cam, a camshaft, a volume cavity, a moving body, a connecting pipe and a spring, wherein the moving body is arranged in the volume cavity, and is hermetically contacted with the inner wall surface of the volume cavity; an installation hole is formed in the left wall surface of the volume cavity; one end of a movable rod passes through the installation hole in the left wall surface of the volume cavity, and is fixedly connected together with the left wall surface of the moving body; and the other end of the movable rod is connected with the camshaft. When the pressure in an air inlet pipe of an engine is higher than the pressure in an exhaust pipe of the engine, the moving body is used for driving the movable rod to move leftwards, and the lift of the inlet valve is increased; and when the pressure in the air inlet pipe of the engine is lower than the pressure in the exhaust pipe of the engine, the moving body is used for driving the movable rod to move rightwards, and the lift of the air inlet valve is reduced. The pressure differential contact point moving system has the advantages of reasonable design, simple structure, and suitability for systems in which the lifts of engine air vales are variable.