White light-emitting diodes (wLEDs) are one of most efficient and environmentally friendly lighting technologies, which are known as indispensable solid-state light sources. At present, the commercial way to produce wLEDs is combining a blue chip with yellow phosphor material as YAG∶Ce3+. The luminous efficacy of the wLEDs could reach the ideal value, but the color rendering is poor, which could be ascribed to the lack of red component in the emission spectrum. Thus, the development of wLEDs is limited in the application of high-quality general lighting, such as showcase lighting, medical illumination and projection display. A promising deep red phosphor, Eu2+ doped CaAlSiN3 (CASN) was prepared by high temperature solid reaction in a gas pressure sintering furnace. In this work, luminescent properties, crystal structure of the CASN were investigated via X-ray diffraction (XRD) and photoluminescence spectra (PL), by applying the structure and bandgap engineering strategies, we have revealed the essential energy transfer mechanism of its luminescence phenomenon. The XRD results indicate that the sample is well-crystallized in the combustion procedure, and its crystal structure has not changed when doped with low concentrations of rare-earth ions. Ca0.992AlSiN3∶0.008Eu2+ phosphors could be effectively excited by a broad emission spectrum extending from 200 to 600 nm, and this broad excitation band could be deconvoluted into five sub-bands by Gaussian fitting. A substantial red spectra is centered at 650 nm under the 450 nm excitation, with a wide broad full width at half maximum (FWHM) of the emission spectrum(91.4 nm), due to the electron transfer of Eu2+ from 5d to 4f. The band structure calculation shows that Ca0.937 5AlSiN3∶0.062 5Eu2+ has an indirect band gap with an energy gap of about 3.14 eV, with the atomic projected Ca-3p, Eu-3d, N-2p, Al-3p, Si-3p states. An optimal spectral model was designed to guide packaging of the phosphor-converted wLEDs, and the influence of the various combination of Ca0.992AlSiN3∶0.008Eu2+ phosphors was studied with the wLED packaging. A super wLED was attained by combining red Ca0.992AlSiN3∶0.008Eu2+ phosphor and green β-sialon phosphor with a blue LED chip, showing a high color rendering index of 92.1, a high luminous efficacy of 101 lm·W-1, and a warm color temperature of 3 464 K. The phosphor of Ca0.992AlSiN3∶0.008Eu2+ is effective to improve color rendering indexes for wLEDs with the contribution of its red spectral part with simultaneous spectral broadening, meanwhile it is of great value in luminous efficacy, color temperature and stability, which means that it is a promising candidate for the red phosphor material for wLEDs.