Yb2+/Dy3+ doped Ca2Si3O2N4 oxynitride phosphors were successfully obtained from the precursor of rare earth doped Ca-3(PO4)(2), at a relatively low temperature without high-pressure environment. Their photoluminescence properties of Yb2+/Dy3+ singly doped Ca2Si3O2N4 phosphors were systematically investigated. A strong emission band is observed at 545 nm originating the typical transition between the allowed 4f(13)5d and 4f(14) configurations of Yb2+ under near ulreoviolet light (370 nm) excitation, which indicates that Yb2+ doped Ca2Si3O2N4 is a promising green phosphor for white LED (WLEDs). Dy3+ doped Ca2Si3O2N4 shows linear emission at 300 nm excitation.