The eosin is used to sensitize dichromated gelatin holographic recording material and photoacoustic spectroscopy (PAS)is adopted to measure its absorption spectrum.The experimental results prove that the eosin is a new and valauable spectral sensitized dye for dichromated gelatin.With the sensitization by the eosin,the dichromated gelatin's absorption becomes higher at 514.5 nm.Thus,this material can be advantageously used for recording full-color holograms and making holographic optical elements. At the same time, these results also show that PAS is an extremely effective way for the measurement of spectral sensitization and photochemical processes of holographic recording materials.