Eu-doped Ca-α-SiAlON phosphors were prepared by a newly-developed thermal-insulation-assisted combustion synthesis method. With Si₃N₄ powders cladding on the reactant mixtures, the duration of the CS system in the high temperature period remarkably enhanced due to the low heat dissipation. The as-produced Ca-α-sialon:Eu₂₊ phosphors feature high purity, good uniformity and outstanding luminescence properties with a yellow emission peaking at 568 nm under a UV or blue light excitation. The excitation and emission intensities for the as-synthesized phosphors were notably improved with the assisted by Si₃N₄ insulating layer.