In order to obtain the different position temperature changes in the process of explosive casting accurate, stability and comprehensive, we designed the temperature monitoring system based on fiber Bragg grating spectral shift. Through the fiber-optic network, the system can monitor the different point temperature of melt-cast explosive real-time. According to the function of linear frequency shift of fiber Bragg grating wavelength with the grating of temperature, we get the temperature of different positions. Four channels share a broadband light source with a coupler. The Bragg wavelengths of the 5 gratings of each fiber are separated from each other. Using the gratings designed, spliced and packaged by our own, we can obtain temperature data through the demodulator. The temperature data was processed by the Origin to draw diagram time-temperature curve. The results show that the measured temperature data of the fiber Bragg grating can meet the requirements of experiment.