In this paper, the light-modulated characteristics of the gene-variant bacteriorhodopsin-D96N molecule film are studied by spectrum response experiment. The absorption enhancement phenomena of BRD96N films at 550—600nm modulated light wavelength are gained, and there are different absorption changes at different monochromatic wavelengths. Using curve-fitting method, it is found that the process of the absorption change includes fast and slow responses with time constants of 30 s and 5 min respectively. Applying the relations between the absorption change and gray-scale image to the write-readout image experiment, the reverse image phenomena in a wavelength range of 550—600nm are analyzed.