We found that when the Al content in the glass was 1 mol%, the specimens only emitted light at wavelengths of 590 and 610 nm, characteristic of a 5D0→7FJ(J=1,2) energy jump of electrons in Eu3+. Further increase the Al content in glass matrix led to a new broad blue-green light emission around 400-550 nm, which can be assigned to 5d-4f energy jump of electrons in Eu2+. Furthermore, the Eu2+-specific broad band emission maximized at 10%Al content, while at the same time, the emission from Eu3+ decreased steadily as the Al content increased. We therefore believe that the presence of Al in aluminosilicate glass triggered an Eu3+→Eu2+ reduction reaction.