The basic knowledge of the fiber Bragg grating (FBG) is introduced, then the working principle, performance and characteristics of several typical demodulation methods are introduced respectively. The diagrams of working principle are given，the advantages and disadvantages of various demodulation methods are discussed. A charge-coupled device (CCD)-based FBG sensing demodulation system is proposed，it uses the reflective imaging system，uses CCD as a detector, and uses the field programmable gate array FPGA to design the drive circuit and signal processing circuit．A wavelength demodulation system which has small size，simple structure, fast demodulation speed, and real-time monitoring capability is realized．These provides the theoretical basis for the practical applications of FBG demodulation techniques and the design of FBG demodulation system.