For removing impurities to improve luminescence properties, Eu2+- activated Sr2Si5N8 red phosphor for white light-emitting diodes (LEDs) was prepared by multiple heat-treatment synthesis which includes carbothermal reduction and nitridation. The X-ray diffraction (XRD) patterns were showed the standard single phase of Sr2Si5N8. With an optimized amount of Eu2+ (2 at. %) dopant, the broad excitation band of Sr2Si5N8:Eu2+ indicated that the phosphor was suitable for application of white LEDs with UV or blue chip, and red emission peak at 628 nm in spectra originating from the 4f65d1→4f7 transition of Eu2+ ion. After third heating process, luminescence properties of the obtained phosphor were improved obviously and higher than commercial YAG:Ce3+ phosphor.