A <TEX>$SrAl_2O_4:Eu^{2+},Dy^{3+}$</TEX> 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 <TEX>$SrAl_2O_4:Eu^{2+},Dy^{3+}$</TEX> phosphor was an amorphous phase. However, a crystalline <TEX>$SrAl_2O_4 $</TEX> phase was formed by calcining at <TEX>$1200^{\circ}C$</TEX> for 4h. From the SEM analysis, also, it was found that the as-synthesized <TEX>$SrAl_2O_4:Eu^{2+},Dy^{3+}$</TEX> phosphor was in irregular porous particles of about 50 <TEX>${\mu}m$</TEX>, while the calcined phosphor was aggregated in spherical particles with radius of about 0.5 <TEX>${\mu}m$</TEX>. The emission spectrum of as-synthesized <TEX>$SrAl_2O_4:Eu^{2+},Dy^{3+}$</TEX> 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 <TEX>$SrAl_2O_4:Eu^{2+},Dy^{3+}$</TEX> 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.