Reaction-bonded silicon carbide square beams are suitable for the load-bearing structural frames of tunnel kilns, shuttle kilns, double-layer roller hearth kilns, and other industrial kilns. This product offers high load-bearing capacity at elevated temperatures, remains unbent and undeformed during long-term use, and has a service life several times longer than that of materials made from other substances. It is an ideal kiln furniture for industries such as sanitary ceramics and electroceramics. The product exhibits excellent high-temperature flexural strength, thermal shock resistance, and oxidation resistance. It maintains its shape over prolonged use, significantly reduces energy consumption, and does not increase the weight of kiln cars.