The Y2SiO5:Ce3+/PMMA composites were prepared by in-situ polymerization with blue photoluminescent powder Y2SiO5:Ce3+ and poly methyl methacrylate (PMMA) as starting materials. The obtained samples were characterized by XRD, FT-IR, SEM, etc. Results show that the Y2SiO5:Ce3+ luminescent powder with particle size of 0.7~2.0 μm has the X2-monoclinic crystal structure and is homogeneously distributed in the PMMA. Excited by the ultraviolet light with the wavelength of 365 nm, the Y2SiO5:Ce3+/PMMA composites exhibit the blue photoluminescence and the transparency of blue photoluminescence achieves a high value of 75%. Consequently, the obtained Y2SiO5:Ce3+/PMMA composites can be used to fabricate the transparent luminescent apparatus.