The present invention relates to the field of methods for preparing silicon carbide nanowires. The method for preparing silicon carbide nanowires described in this invention is as follows: place an oxygen-free silane in an alumina crucible or alumina boat, place the alumina crucible or boat on a high-temperature resistant plate, then push the high-temperature resistant plate into a high-temperature furnace, evacuate the oxygen inside the furnace, and introduce inert gas protection at a rate of 6 - 15 sccm. Raise the furnace temperature to 1000 - 1100°C at a rate of 5 - 15°C/min, maintain the temperature for 1 - 3 hours, and then naturally cool down to room temperature. The products obtained by the method for preparing silicon carbide nanowires described in this invention are all silicon carbide nanowires, which have a length that is two orders of magnitude higher than those prepared by existing methods. Moreover, the preparation method is simple, the raw materials are cheap and readily available, the equipment requirements are simplified, and the cost is low.