Mn4+-activated oxide phosphors, owing to their desirable spectral features, eco-friendly and low cost, are emerging as a new class of non-rare-earth red phosphors for warm white LEDs. However, these phosphors possess low photoluminescence quantum efficiency excited by blue chip currently. Herein we report an iso-structural solid solution of Ca14Zn6Ga10?xAlxO35: 0.15Mn4+ (0 ≤ x ≤ 10) synthesized by a traditional solid-state reaction route. The microstructure and luminescent performance of this red-emitting phosphor are in-vestigated in detail with the aids of X-ray diffraction, diffuse reflection spectra, photoluminescence spectra/decay/QE, and temperature-dependent PL/QE measurements. Blue shift of energy peaks of 4A2→ 4T1 and 4A2→4T2 transition is illustrated by the Tanabe-Sugano diagram and the configurational coordinate diagram. The crystal field strength (Dq) and the Racah parameters (B and C) are carefully calculated to estimate the nephe-lauxetic effect β respectively. Particularly we achieve extal and intal quantum efficiencies as high as 26.1％ and 40.3％ for Ca14Zn6Ga6Al4O35:0.15Mn4+excited by 466 nm, the highest one ever reported in Mn4+activated oxide phosphors under the similar condition.