A large quantity of 3C-SiC nanowires (SiCnws) with high purity were fabricated via carbothermic reduction method combined with a novel two-stage temperature program. At the first temperature stage, the reactants were kept at 1600 degrees C for 4h to promote the formation of SiC nucleus and SiO intermediate gas. Then they were cooled to 1350 degrees C for 2h at the second stage for the growth of SiCnws with fewer defects. Compared with the conventional single temperature method at 1600 degrees C for 6h, the product prepared by this new strategy exhibits large yield and high purity with a narrow diameter range. As for the reaction mechanism, solid-solid and solid-vapor reactions occurring between SiO2, SiO and C dominate at the first stage. While vapor-vapor reaction between SiO and CO plays an important role at the second stage. Furthermore, photoluminescence (PL) properties were measured under the room temperature. A sharp violet light emission peak with a significant blue shift is observed at 401nm compared to bulk 3C-SiC.