A thermocautery block is formed by mixing alumina, zirconium silicate, feldspar, pottery stone, siliceous limestone, kaolin, Gairome clay (Japan), and black soil with water; evenly stirring the mixture; compressing, dehydrating, and extruding the mixture into polygonal blocks; and drying, kilning, and cooling the blocks. The thermocautery block has a high density and a hardness higher than 6.0, and could store thermal energy after being heated for a short time. The stored thermal energy is progressively released via superficial areas of the block other than corners thereof to produce the effect of progressive temperature rise.