In this article, a novel magnesium-catalyzed co-reduction route was developed for the large-scale synthesis of aligned beta-SiC one-dimensional (1D) nanostructures at relative lower temperature ( 600 C). By carefully controlling the reagent concentrations, we could synthesize beta-SiC rodlike and needlelike nanostructures. The possible growth mechanism of the as-synthesized beta-SiC 1D nanostructures has been investigated. The structure and morphology of the as-synthesized beta-SiC nanostructures are characterized using X-ray diffraction, Fourier transform infrared absorption, and scanning and transmission electron microscopes. Raman and photoluminescence properties are also investigated at room temperature. The as-synthesized beta-SiC nanostructures exhibit strong shape-dependent field emission properties. Corresponding to their shapes, the as- synthesized nanorods and nanoneedles display the turn-on fields of 12, 8.4, and 1.8 V/mu m, respectively.