A design scheme of demodulation system based on field programmable gate array (FPGA) for fiber Bragg grating(FBG) temperature sensor is proposed. Using the principle of (direct digital synthesizer (DDS), the drive voltage of Fabry-Perot (F-P) filter is constituted by FPGA. It can achieve 10 V. Many analog-to-digital (A/D) converters are controlled by FPGA to make up the successive data acquisition module. It can get the result in real time. The comb-shaped filter is used to correct the system in time. The index of a FBG sensor is calibrated confirmed. The system is used for denodulation between 30 ℃ and 100 ℃, and electronic thermometer and spectrograph are used to get the accurate result. The different records can be compared to assess the performance of system. The mean error of temperature is 0.19129 ℃, and the minimum temperature is 0.045 ℃, with the resolution being 1 pm.