A large-scale crystalline silicon nanowires (SiNWs) with a diameter of ∼30 nm andlength of tens of micrometers on Al2O3 templates andsilicon wafers were synthesizedby the thermal evaporation of silicon monoxide (SiO). The SiNWs were measuredby transmission electron microscopy, scanning electron microscopy, X-ray di4raction andRaman spectroscopy, respectively. It was pointedout that the SiNWs possessedthe well crystalline structure. Therefore, it is consideredthat SiO couldbe usedas Si sources to produce larger-scale SiNWs andcrystalline SiNWs may grow from amorphous nuclei.