In order to improve the demodulation accuracy of fiber grating,a broadband Fiber Bragg Grating(FBG) with a 3 dB bandwidth within 1~3 nm and self-correlation algorithm demodulation system are designed.A linear array CCD sensor is used to detect grating spectrum and tested in the wavelength peak finding experiment.Wavelength spacing between pixels is fixed in a CCD sensor,so higher bandwidth FBG can get more effective pixels,and self-correlation algorithm only demodulates the excursion of spectrum in sensing and testing,thus,background noise is offset and spectral anomaly caused by writing or packaging improperly is eliminated.The precision of the grating center wavelength demodulation is improved.Experimental results show that using self-correlation algorithm demodulate broadband FBG and chirp FBG,the error is respectively 54.05% and 40.87% lower than Gauss algorithm.Self-correlation algorithm can make the chirped grating reach the demodulation accuracy of normal grating.Also the error of broadband FBG is only 50% of chirp FBG error.