A proximity switch for an oil cylinder comprises a pressure sensor, a proximity switch body, a temperature compensation system, a single chip microcomputer, a storage battery and a shell; a cavity isformed in the shell and internally provided with the pressure sensor, the proximity switch body, the temperature compensation system, the single chip microcomputer and the storage battery; the pressure sensor is internally provided with an elastic sensitive element, a resistance strain gauge and a sensing chip; the elastic sensitive element is tightly attached to the resistance strain gauge; the proximity switch body is internally provided with an electrified coil, a high-frequency oscillator, an oscillation detector and a signal amplifier; the electrified coil is connected with the high-frequency oscillator in series; the oscillation detector transmits a signal to the signal amplifier through a circuit; the temperature compensation system is internally provided with a winding electroplated multiple-contact thermo-electric pile and a temperature sensor, and the winding electroplated multiple-contact thermo-electric pile is provided with cold and hot contacts; the storage battery is connected with the pressure sensor, the proximity switch body, the temperature compensation system and the single chip microcomputer through a circuit; and the single chip microcomputer is internally provided with a wireless data transmission device.