Fabry-Perot (F-P) interferometer is a kind of multiple beam interferometer. It has very high spectral resolution, and can be used to research fine structure of the matter. The application of F-P interferometer is limited by the free spectral range. The fine structure of the matter will not be got when the bandwidth of the light surpass the free spectral range. Based on the F-P interferometer, we describe the relationship between the interference pattern and the spectral curve as equation sequence. The equation sequence is solved by the singular value decomposition, and the wide bandwidth spectral curve will be got. By this way F-P interferometer can be used as a spectral imaging instrument. But the algorithm is sensitivity to the noise of the interference pattern. After some simulation work, we find the noise of the interference pattern should be less than 0.2%.