Phenanthrenequinone (PQ) doped poly(methyl methacrylate) (PMMA) has been proven to be available material for volume polarization holographic recording. In our work, we introduced benzyl methacrylate (BzMA) into the PQ/PMMA to increase the concentration of PQ (up to 1.15 wt%) within the polymeric media. The enhancement of concentration of PQ brings a mean for improving performance of material. Compared with the pure PQ/PMMA, photoinduced birefringence and diffraction intensity were multiplied by introducing BzMA. This investigation can provide a significant foundation for improving polarization holographic characteristics of PQ/PMMA by modifying the chemical composition of the material.