The invention belongs to mine pressure on-line monitoring systems, and discloses a working face mine pressure on-line monitoring system based on fiber grating sensing. According to the monitoring system, a plurality of measurement points are selected on a working face in a pit, one monitoring system is installed inside each measurement point, a hydraulic control valve of each monitoring system is installed in a hydraulic support and is connected with a pressure guide hole of an intrinsic safety type fiber grating pressure meter through an oil pipe, an optical signal of the intrinsic safety type fiber grating pressure meter is transmitted to a fiber grating demodulator on the ground through an optical fiber and a mining optical cable, the fiber grating demodulator is demodulated into a digital signal to be transmitted to a computer system, and the computer system carries out real-time monitoring and analysis processing. The working face mine pressure on-line monitoring system based on the fiber grating sensing has the advantages of being simple in installation, adopting full-optical measurement and optical fiber transmission, being capable of effectively avoiding influence of electromagnetic interference, greatly improving monitoring accuracy due to adoption of a temperature compensation grating for compensating a temperature error, and being capable of timely providing a working face mine pressure monitoring and predicting result so as to bring convenience to production and scientific researches of a guidance site.