Three kinds of Long afterglow Sr4Al14O25: Eu2+, Dy3+ phosphor samples with various Eu2+ contents were synthesized. When the concentration of doped Eu2+ in the host was less than 0.012 mol, the emission spectra of Sr4Al14O25: Eu2+, Dy3+ has two peaks at 407 nm and 494 nm respectively, which is ascribed to two types of Eu2+ sites existing in Sr4Al14O25 matrices crystal. But the 407nm emission peak disappeared slowly with the concentration of doped Eu2+ increasing. Based on the Sr4Al14O25 crystal structure, excitation and emission spectra, the energy transfer model has been established, and a reasonable explanation was given for the experimental phenomena. In addition, the decay curves indicate that these Sr4Al14O25: Eu2+, Dy3+ phosphors have obviously a long afterglow. Especially in phosphor, the afterglow can last over 20 h in the light perception of the human eye.