Silicon nanowires(SiNWs) were prepared by rf-magnetron sputtering at 260 ℃. The grown temperature of SiNWs is below the melting point of Si-Bi alloy. The density of SiNWs first rises and then falls as the growing temperature increases. Hydrogen radicals treatment can reduce the synthesis temperature of SiNWs. The nano-crystalline ratio is in inverse proportion to grown temperature in SiNWs.