The invention discloses a bore-tunneling electrical ahead monitoring device based on an optical fiber current sensor, and a detection method thereof. The bore-tunneling electrical ahead monitoring device is composed of a constant current source, a voltmeter, a laser light source, the optical fiber current sensor and an anchor rod. A tunneling part of a tunnel boring machine (TBM) is supplied with a constant current I, a circle of an optical fiber winds around the rear part of a cutterhead and the rear part of a shield, the magnitude of current on each of the cutterhead, the shield and TBM rear guaranteeing equipment can be obtained by using the optical fiber current sensor, and voltage on the shield is measured for calculating apparent resistance of a geologic body, so as to judge water content and rock class of the geologic body. Compared with the traditional bore-tunneling electrical ahead monitoring method, the bore-tunneling electrical ahead monitoring device based on the optical fiber current sensor omits a great deal of pre-insulating operation.