A new alkali metal borate β-NaSrBO3 was synthesized by a standard solid-state reaction method and was determined to be a high-temperature phase of α-NaSrBO3 by the variable temperature XRD diffraction.Ce3+ activated β-NaSrBO3:Ce3+ show an intense blue-emitting at 424 nm under 358 nm excitation,which is ascribed to the parity allowed 4f-5d transitions of Ce3+ ions.A near-ultraviolet-pumped warm white light emitting diodes(w-LEDs)with β-NaSrBO3:0.05Ce3+ phosphor as the blue composition was fabricated and showed outstanding performance.