The invention discloses a preparation method of a graphene coated silicon carbide nanowire. The technological process is easy to achieve, and the deposition temperature of the silicon carbide nanowire is relatively low, so that the preparation cost is reduced, and the preparation technology is simplified; the graphene coated silicon carbide nanowire obtained through the method is high in straightness and uniform in diameter distribution; when the product is utilized as a reinforcing phase of a ceramic material, the interface bonding between the silicon carbide nanowire and a ceramic matrix can be strengthened; and besides, the graphene on the surface of the silicon carbide nanowire has reinforcing and toughening effects.