A four elements fiber Bragg grating sensing arrays has been interrogated using a tunable Fabry-Perot filter acted as a wavelength scanner and an oscilloscope and a photodector to monitor the distribution of the transmitted intensity in time domain.The sensing signal can be demodulated by comparing the shifted and unshifted spectra and the results are in good agreement with the prospected values.The measured range of the sensing elements can be improved by choosing the gratings with larger reflectivity difference.