Distributed fiber bragg grating sensor is one of the critical application of fiber technique， and the signal demodulation is key to achieve network of sensing system. The basic principle of fiber Bragg grating(FBG) sensors was introduced. Two kinds of demodulation methods being used commonly at home and abroad in recent years were given: wavelength scan demodulation and parameter transform demodulation, and some typical techniques in these demodulations methods were discussed particularly, the advantages and disadvantages were concluded respectively，the basis for the design of distributed FBG sensing demodulation system was provided.