The invention discloses a cracking-resistant high-strength insulating brick which comprises the following raw materials in parts by weight: 60-100 parts of Portland cement, 10-20 parts of rice husk complex, 30-80 parts of magnesia cement, 2-10 parts of coal cinder, 4-10 parts of sepiolite powder, 1-3 parts of microcrystalline cellulose, 4-9 parts of talcum powder, 1-2 parts of an early strength agent, 1-2 parts of an enhancer, 50-150 parts of water, 1-3 parts of polystyrene foam particles, 1-2 parts of a colloidal agent and 0.2-1 part of a liquid foaming agent. The rice husk complex is prepared according to the following process steps: adding rice husks into a potassium hydroxide solution, raising the temperature, stirring, filtering, performing vacuum drying, adding graphene oxide to be uniformly mixed, carbonizing, uniformly grinding, adding glycerin, sodium polyacrylate and water to stir, adding hydroiodic acid to stir, filtering, washing and drying, thereby obtaining the rice huskcomplex. The cracking-resistant high-strength insulating brick provided by the invention is extremely high in flexibility, difficult to crack, high in strength and excellent in thermal insulation effect.