The invention relates to a differential pressure sensor for a switching value. The differential pressure sensor comprises a shell body and a signal control unit, wherein an inner cavity of the shell body is provided with a high-pressure chamber and a low-pressure chamber, a first pressure sensing film is arranged in the high-pressure chamber, a second pressure sensing film is arranged in the low-pressure chamber, a connecting rod is arranged between the first pressure sensing film and the second pressure sensing film, two ends of the connecting rod are adhered on the first pressure sensing film and the second pressure sensing film, a pressure value adjusting knob is arranged at one end of the connecting rod, the signal control unit is arranged in an electrical chamber of the shell body, and comprises a sensing microswitch which is connected with a circuit function module, and the circuit function module is connected with a central processor (ECU) through a trigger circuit. The differential pressure sensor can be used for accurately acquiring a pressure drop of a fluid passageway component, outputting a reliable, simple and manageable signal, and driving an indicator lamp or transferring a signal to the central process (ECU) by only outputting an indication signal at a certain point, so that the signal is stable and simple, and cannot be affected by a severe environment.