An efficient blue-green phosphor, $Sr_4Al_{14}O_{25}:Eu^{2+}$, $Dy^{3+}$, was prepared by solid-state synthesis method. $B_2O_3$ was used as a flux for the synthesis of phosphor materials. The different mol % of $B_2O_3$ was employed during the synthesis. X-ray powder diffraction (XRD) confirmed the formation of $Sr_4Al_{14}O_{25}:Eu^{2+}$, $Dy^{3+}$ phosphor in an orthorhombic phase. The synthesized phosphor materials were further investigated by XRD, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence studies. The phosphor, $Sr_4Al_{14}O_{25}:Eu^{2+}$, $Dy^{3+}$ shows broad band ultraviolet (UV) excited luminescence in the blue-green region (${lambda}_{max}$= 491 nm) due to the transition from the $4f^65d^1$ to the $4f^7$ level of the $Eu^{2+}$ ion. The phosphor material with 75 mol % $B_2O_3$ shows high brightness and long persistent luminescence whereas the phosphor material without $B_2O_3$ shows no emission and persistence of luminescence.