The invention discloses an earthquake monitoring device. The device consists of a central control terminal and a sensor probe under ground, wherein, a light pulse signal is generated from a light source part of the central control terminal, transmitted to the underground sensor probe in an deep ground environment over an optical fiber, then the light pulse signal is changed into 3 discrete modulated pulse signals in time domain after being vibrated, strained and temperature-modulated in the probe in the deep ground, and the modulated pulse signals return to an information demodulation section of the central control terminal for photoelectric conversion, amplification, data processing to complete demodulation, thus realizing real-time monitoring and alarming of parameters of vibration, strain and temperature in the deep ground. The device has the advantages of low production cost, simple installation, high accuracy and good practicability, being convenient to form a network of stations, and realizing stereoscopic multiparameter monitoring on the deep ground environment in a large range.