The invention discloses a method for preparing reaction sintered silicon carbide ceramics. Firstly, waste silicon carbide powder, silicon carbide powder material, adhesive and solvent are added into a ball mill in proportion, and then the mixed powder is put into a drying oven to dry, and then Put the powder into the mold, pressurize it into a blank, then crush the blank, sieve, and then evenly distribute the sifted powder in the cavity of the mold, mold it again into a green body, and heat up and dry it after debinding , place the green body in a graphite crucible, add metal silicon into the crucible, put the crucible into a high-temperature vacuum sintering furnace for sintering, and then lower the temperature to obtain a reaction-sintered silicon carbide ceramic. The invention has a simple process and is suitable for large-scale industrial production, and can not only effectively solve the problems of environmental pollution and resource waste caused by a large amount of silicon carbide waste, but also reduce the raw material price of reaction sintered silicon carbide materials.