Abstract: Blue-purple long afterglow phosphors SrAl₂O₄:Eu²⁺,Dy³⁺ were synthesized by conventional solid phase reaction method. There are two excitation peaks at 345nm and 405nm, and a emission peak at 520nm. The scanning electron microscopy （SEM） images indicate the crystallinity of phosphors is enhanced greatly with the increase of H₃BO₃ concentration.Determined by X-ray power diffraction（XRD）, SrAl₂O₄ belong to monolicnic system remains the main phase of the phosphors,while the new aluminate is observed .From analyzing the thermoluminescence curves, when the mole ratios of H₃BO₃ in SrAl₂O₄ is 17%, the most powerful trap is 0.59eV corresponding to peak at 329K, which improves the afterglow properties of phosphor.The trapped depths are acquired by fitting the experimental results with general order kinetic model.