Nano-sized SrAl2O4:Eu2+,Dy3+ phosphors with good monodispersity and narrow size distribution were synthesized by the coupling of water-in-oil (W/O) microemulsion with coprecipitation method. The phase composition, morphology, crystallinity, excitation spectra, emission spectra, and afterglow decay of SrAl2O4:Eu2+,Dy3+ nanophosphors were measured. It was found that the amount of surfactant that was used had an important effect on the shape and average size of the phosphor particles. SrAl2O4 phase of the phosphors showed an increase with the increase in calcination temperature.When the calcination temperature reached 1150℃, the fine crystal of SrAl2O4 was formed and the long afterglow luminescence could be obviously observed. In comparison with the samples prepared by the high-temperature solid-state method,the calcination temperature showed an obvious decrease and a clear blue shift occurred in the excitation and emission spectra of the sample. The afterglow time could be more than 8 h.