A well-designed and assembled apparatus for producing silicon nanoparticles by CO 2 laser-driven pyrolysis of SiH 4 is shown. The effects of process parameters (chamber pressure, laser power, gas composition) on the nano-silicon characteristics (average particle size, size distribution and shape) are systematically investigated. The produced silicon nanopowders are characterized and analyzed, demonstrating the produced particles are much smaller and much more uniform in size than the commercial products and those previously reported. The impressive productivity and yield are also discussed. This research allows a better understanding of the influences of processing parameters on silicon nanopowders, shows a controllable way of producing the desired powders, and paves the way to commercialization.