Abstract: The present disclosure provides a silicon-based direct band gap light-emitting material compatible with the CMOS fabrication process, and a preparation method thereof. The method comprises steps of: preparing a silicon-based material, wherein the silicon-based material is a germanium material or a silicon-germanium alloy; filling some of lattice interstitial sites of the silicon-based material with noble gas atoms and/or other atoms with a low atomic number, so as to expand the lattice volume in order to transform the band structure from indirect band gap to direct band gap, thereby obtaining a silicon-based direct band gap light-emitting material. The present disclosure also provides a silicon-based light-emitting device.