The invention provides a fiber grating temperature sensing system for detecting temperatures of inflammables and explosives. The system comprises an amplified spontaneous emission (ASE) broadband source, a circulator, an optical switch, an optical switch drive device, a fiber Bragg grating (FBG) temperature sensor, a holographic volume phase grating, a collimating lens, a condenser lens, a photoelectric detector, a control circuit, a digital signal processing (DSP) circuit, a storage and an upper computer, wherein the FBG temperature sensor is stuck onto the surfaces of the inflammables and explosives, and wavelength drifting information is demodulated by utilizing a holographic volume phase grating demodulation method, so that temperature variation of the FBG temperature sensor is obtained, namely, the temperature variation of the inflammables and explosives, and the temperature of the inflammable and explosive is finally obtained. Fiber grating temperature sensing system for detecting temperatures of inflammables and explosives has the advantages that the sensitivity and the stability are high, optical fiber sensors have strong anti-electromagnetic interference, anti-shaking, moisture resistant, corrosion resistant and the like competences, therefore the system can also be used normally for a long time in severe environments. The optical fiber sensors have the advantages of being light in weight, small in size and the like.