The invention relates to a differential pressure control valve, which comprises a valve body, wherein a main valve core and a control valve core are arranged in the valve body; two valve core cavity bodies are connected through an oil duct; one end of the main valve core stretches into the oil duct and is matched with the oil duct; the other end of the main valve core is connected with a reset spring; an X oil port, a Y oil port and a T oil port are formed in the valve body; a C cavity close to the end part of the valve body and a D cavity close to the oil duct are respectively arranged on two sides of the control valve core; the X oil port is communicated with the C cavity and a system pressure oil duct P; the Y oil port is communicated with the D cavity; the T oil port is communicated with the oil duct. According to the differential pressure control valve, when the system pressure is lower, the control valve core and the main valve core are applied with smaller pressure, and the reset spring cannot be pushed, so that an oil inlet and an oil outlet are communicated; when the pressure is gradually increased to exceed a critical state, the reset spring is moved rightwards under the joint action of the control valve core and the main valve core, so that the oil inlet and the oil outlet are separated. The whole process does not need manual or electronic control, so that the differential pressure control valve is suitable for being used in seawater for a long time; the position of a spring seat is adjusted through an adjusting screw, and the pressure of the reset spring can be changed, so that the open and close pressure is changed.