SiAlON-based phosphor has become a research hotspot due to its excellent chemical and physical stability. Especially in the LEDs field, it has received extensive attention in recent years. Rare earth doped SiAlON phosphor is expected to become a new generation of lighting source. However, due to the lack of cyan light emission, the color rendering performance of white-LED (wLED) is often insufficient. In this research, β-Si₅AlON₇:Eu phosphors were synthesized by the traditional high-temperature solid-state route. The structure, morphology, elements and valence states were examined. The wavelength range of excitation spectrum and emission spectrum of Si₅AlON₇:Eu, as well as the thermal quenching performance were studied. It is found that the excitation wavelength range covered the ultraviolet to blue region, and the emission spectrum is a typical broad feature of Eu²⁺ transition. At 300 ℃, the emitted light intensity of the sample can still reach about 40% that of the room temperature, while the thermal activation energy (E_a) reaches 3.7 eV. Compared with the commercial YAG:Ce³⁺ (YAG) phosphor, the thermal stability of Si₅AlON₇:Eu is improved. The wLED with high color rendering of R_a=87 is realized after compounding with the blue chip, and the corresponding color temperature reaches the warm white light range (CCT=4501 K). In this study, SiAlON-based cyan emission is realized, and the phosphor with excellent thermal stability is obtained. Compared with commercial YAG, it also has obvious advantages in the sustainability of luminescence.