Large-scale ultra-long (even up to several centimeters) α-Si₃N₄ nanowires have been prepared using N₂ as the nitrogen source, SiO or a mixture of Si and SiO₂ as the silicon source, N₂ and Ar as the barrier gas, and CH₄ as the reducing gas by a simple catalyst-free CVD route under superatmospheric pressure conditions. The nanowires grown on ceramic boat or corundum substrates, with lengths of several millimeters, even up to several centimeters, and average diameters of around 40nm, were composed of a single-crystal α-Si₃N₄ core along the [210] direction and amorphous SiO₂ shell of about 1–10 nm thick. The total gas pressure is an important factor for the synthesis of the large-scale centimeter-long α-Si₃N₄ nanowires, which can easily adjust the pressure of the vapors to supersaturation condition. The growth of the nanowires was governed by the vapor–solid mechanism. The α-Si₃N₄ nanowires showed an intensive blue light emission centered at 450 nm at room temperature, which arise from the recombination between the intrinsic conduction band edge and Si dangling bonds.