A novel photopolymer storage medium for holographic storage is presented. In particular, the refractive index of the monomer methyl methacrylate is much lower than that of the binder epoxy resin solidified by mxylylenediamine, and the material can be developed into samples with dimension stability and high optical quality and thickness of several millimetres or more. Some none-polymeric macromolecule impurity is uniformly mixed into the medium to aid the monomer diffusing and to enhance the diffraction efficiency. A holographic recording medium of 0.8 mm thickness has been fabricated, and relative theoretical analysis and experiments are presented.