In recent times, rare-earth-doped oxynitride or nitride compounds have been reported to be photoluminescent and may then serve as new phosphors because of their good thermal and chemical stabilities. In this study, β-SiAlON:Eu2+ oxynitride phosphors with compositions of Eu2+xSi6-zAlzOzN8-z were successfully prepared using GPS (gas pressured sintering) process. The phase purity, microstructure, luminescent and thermal quenching properties for the prepared β-SiAlON:Eu2+ phosphors were investigated in detail. The obtained β-SiAlON:Eu2+ phosphors had a rod-like morphology with a uniform size of 3-5 μm in length and 0.5-1 μm in diameter. The β-SiAlON:Eu2+ phosphors absorbed UV-visible spectral region, and showed a single intense broadband emission in visible range. The effects of the Eu2+ doping concentration (x) and Si/Al ratio (z) on the optical properties for the β-SiAlON:Eu2+ were discussed under consideration of concentration quenching and nephelauxetic effect. The temperature dependence on photoluminescence (PL) properties was investigated from 25 to 275 °C, and the activation energies (ΔE) for thermal quenching of the prepared β-SiAlON:Eu2+ were determined by Arrhenius fitting. The experimental results clearly indicates that the prepared β-SiAlON:Eu2+ phosphors have great potentials as a down-conversion green phosphor for white light emitting diodes (LEDs) utilizing near UV or blue LEDs as the primary light source.