The photochemical theoretical model and dynamic parameters of the photopolymer are studied. A new holographic photopolymer sensitized by methylene blue (MB) and erythrosine B (ErB) is prepared .This material is tested to obtain transmissivity versus exposure condition and the photochemical parameters with the fixed exposure wavelength of 633nm and intensity of 65 mW/cm2. Experimental results show that photobleaching coefficient k and quantum yield Φ of photopolymer increase with the exposure wavelength and increase of light intensity. At the intensity of 65 mW/cm2 transmissivity drops under short wave, photobleaching coefficient k is negative, but the molar-absorption coefficient ε shows different changes in different conditions.