The invention discloses a method for preparing reaction-sintered grouting-formed silicon carbide ceramics. Two kinds of silicon carbide micro-powders which are produced by a jet mill and which are saturated by particle shaping have a particle diameter of 50 [mu]m and 5 [mu]m, and the relative blending ratio ranges from 1:1 to 10:1, pigment carbon black or metallurgical carbon black with a particlesize of 20 nm to 100 nm is taken as a carbon source, the ratio of addition is 1% to 15%, novel high-efficiency binders are adopted and are multiple or all of a group consisting of acrylamide, polyvinylpyrrolidone, polycarboxylic acid, polyvinyl formal, amino ethanol, tetramethylammonium hydroxide, maleic anhydride and polyacrylic acid, and deionized water in a volume ratio of 10% to 40% is adopted. By controlling the suitable silicon carbide raw material particle size and particle size grading, the suitable proportion of carbon and the suitable binders, the carbide ceramics which are low in free silicon residue uniformly distributed, are basically free of free carbon and have high product density and product strength can be prepared, and the reaction-sintered grouting-formed silicon carbide ceramics can be applied to the fields such as lightweight armor, aerospace materials, and reactor vessels.