The invention relates to a silicon carbide coating and a preparation method thereof, and belongs to the technical field of inorganic functional coating materials. The preparation method of silicon carbide comprises the following steps: respectively preparing a first coating sizing agent and a second coating sizing agent, wherein the first coating sizing agent is prepared from phenolic resin, Si powder and SiC powder with a weight ratio of 3:(3 to 5):(0.5 to 1.5), and the second coating sizing agent is a silicified sizing agent; coating the surface of a carbon-containing material with the prepared first coating sizing agent, curing to obtain an inner coating layer, then coating the surface of the inner coating layer with the prepared silicified coating sizing agent, and curing to obtain an outer coating layer; performing high temperature vacuum sintering on the carbon-containing material on which the outer coating layer is formed, thus obtaining the silicon carbide coating. According to the silicon carbide coating provided by the embodiment of the invention, the inner coating layer and the outer coating layer can be formed by high temperature sintering for once, quick formation of the high-quality silicon carbide coating is realized, the preparation process is greatly simplified, and a preparation period is shortened by 50 percent or more; the method adapts to quick preparation of carbon-containing materials with different structures, different sizes and special shape and component coatings thereof.