The invention provides a kind of polymer grafted long afterglow phosphor which composed of alkali earth aluminate phosphor grafted by polymer through coordination bond and a method for producing the same. The method for producing a polymer grafted phosphor comprise two steps: the alkali earth aluminate activated by rare earth ions is coordinated with difunctional ligand to form a coordinated long afterglow phosphor; The coordinated long afterglow phosphor was dispersed in organic solvent at 40.about.130.degree. C., the ligand was initiated by initiator and could copolymerize with other polymerizable monomer to form the polymer grafted long afterglow phosphor. The formed phosphors have good water resistance and luminescent properties. They can be widely used in fields of luminescent coatings, paints and plastics.