A SrAl2O4:Eu2+,Dy3+ phosphor powder with stuffed tridymite structure was synthesized by glycine-nitrate combustion method. The luminescence, formation process and microstructure of the phosphor powder were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectroscopy (PL). The XRD patterns show that the as-synthesized SrAl2O4:Eu2+,Dy3+ phosphor was an amorphous phase. However, a crystalline SrAl2O4 phase was formed by calcining at 1200oC for 4h. From the SEM analysis, also, it was found that the as-synthesized SrAl2O4:Eu2+,Dy3+ phosphor was in irregular porous particles of about 50 μm, while the calcined phosphor was aggregated in spherical particles with radius of about 0.5 μm. The emission spectrum of as-synthesized SrAl2O4:Eu2+,Dy3+ phosphor did not appear, due to the amorphous phase. However, the emission spectrum of the calcined phosphor was observed at 520 nm (2.384eV); it showed green emission peaking, in the range of 450~650 nm. The excitation spectrum of the SrAl2O4:Eu2+,Dy3+ phosphor exhibits a maximum peak intensity at 360 nm (3.44eV) in the range of 250~480 nm. After the removal of the pulse Xe-lamp excitation (360 nm), also, the decay time for the emission spectrum was very slow, which shows the excellent longphosphorescent property of the phosphor, although the decay time decreased exponentially