Long afterglow SrAl2 O4: Eu2+, Dy3+ phosphor was synthesized by microemulsion method. The synthesized phosphor was characterized by XRD. XRD pattern indicates that the phosphor has monoclinic SrAl2 O4 crystal structre.The microstructure of the phosphor was investigated by SEM and TEM. The excitation spectrum, emission spectrum and afterglow decay curve were measured, the wide range of excitation wavelength indicated that the luminescent material could be excited by the light from ultraviolet ray to visible light, and the emission maximum was found to peak mainly at λem of 525 nm. The sample excited by ultraviolet visible light could emit bright green light.