The invention relates to an underground monitoring device of an intelligent well, comprising a pressure sensor, a temperature sensor, a displacement sensor, a circuit short section, a cable and a cable protective pipeline, wherein the pressure sensor, the temperature sensor and the displacement sensor are arranged on oil and gas producing pays; the circuit short section includes acquisition, communication and control; the pressure sensor, the temperature sensor and the displacement sensor are connected in a circuit signal manner; the free slide bar end of the displacement sensor is connected to a sliding sleeve; the circuit short section is connected with an electromagnetic directional valve; the electromagnetic directional valve is connected with a hydraulic cylinder controlling the opening degree of the sliding sleeve; and the circuit short section acquires pressure, temperature and displacement signals, receives a ground command, completes the communication between the producing pays and the ground and between the ground and the ground, sends timing impulses to drive the electromagnetic directional valve to operate and controls the sliding sleeve to be opened. The invention mainly completes the opening degree feedback of the sliding sleeve of an oil duct and the pressure and temperature monitoring of oil and gas layers and controls the underground electromagnetic directional valve to operate according to a ground production regulation command and realizes the regulation of the opening degree of the sliding sleeve, thereby achieving the purposes of state monitoring and production regulation and control of the underground oil and gas layers.