In the presentwork,mixture of five different concentrations (2, 4, 6, 8 and 10 wt%) of an alkali earth aluminate photoluminescent pigment powder (AREAPP) with poly (methyl methacrylate) (PMMA) were prepared. The pigment has the composition formula ofMeO.xAl2O3.ySiO2:Eu (Me = Ca, Mg, Sr,Ba, x = 0.5-2.0, y = 0.005-0.5)which is activated by rare earth element (Eu). Thermal analyses [differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)] as well as Fourier transform infrared spectroscopy (FTIR) were employed to characterize and reveal the miscibilitymap and the relationship of the structure properties. Fromthe results, we can find that the organic parts are attached with the inorganic parts in the PMMA/AREAPP mixtures. Also, the obtained results of the thermal analyses showed variations in the phase transition temperature on the lower temperature side indicating themiscibility of the systems. The changes in the phase transition temperature on the high temperature side, shape and area were attributed to the different degrees of crystallinity.