The concentration of photosen-sitizer is an important factor affecting the properties of holographic materials. Most researchers use doping or copolymerization methods to increase the saturation dissolvability of photo-sensitizer. However, the addition of multiple components will reduce the molecular mass of the photoproducts and the polymer substrate, resulting in poor stability of the grating. In this paper, we studied the solubility of phenanthraquinone (PQ) in MMA at different temperatures. At 60 °C, the solubility of PQ could reach 1.8%. Meanwhile, we found that the thermo-initiator concentration of 2,2-Azobis(AIBN) affected long-chain carbon polymerization. Therefore, proper concentration balance has a huge impact on the performance of the materials. Finally, we obtained a relatively suitable concentration balance of PQ/PMMA photopolymer, making it more suitable for volume holographic data storage.