Abstract: The transmittance curves of the photopolymer which sensitized by different dual-dyes were fitted based on the basic photochemical reaction process of the photopolymer and its theoretical function model, and the parameters in the theoretical model of the photochemical reaction were obtained. A new method to realize the curve fitting by MATLAB and obtain the photomechanical parameters in the photopolymer, based on the theoretical model and experimental data, was analyzed. The analysis shows that the R-Square of fitting statistics for three photopolymers are 0.9687,0.9958 and 0.9902 respectively when the exposure wavelength is 633nm and the exposure intensity is 65mW/cm2. It means that the fitting method is successful.