The effect of mixing ratio, firing temperature and matrix glass composition on afterglow luminance property of SrAl 2 O 4 : Eu 2+ ,Dy 3+ -glass composites were investigated. As a result, the brightness showed a maximum at 35 mass % of the mixing ratio of the phosphor for the glass and 780°C of the firing temperature. And it was increased with decreasing the Na 2 O content of the matrix glass. From the backscattered electron and the EDX analysis, it is thought that the intermediate layers generated between the phosphors and the Na 2 O-poor matrix glass work as antireflective and the phosphor particles in the composite emit phosphorescent light more efficiently. As higher the basicity parameter, B, the intermediate layer was clearer, which means that the reactivity at the phosphor/glass boundaries was lower, and the narrow reaction layers was formed.