The invention discloses a heat preservation brick which comprises a hollow brick serving as a brick body shell and a cement foam material accommodated in the cavity of the brick body, wherein the hollow brick comprises the following raw materials: cement, construction waste earth, ceramsite, lime and perlite; the cement foam material comprises the following raw materials: cement, calcium carbonate, calcium sulfate, sialite, calcium borate, corn stalk powder, AR glass fiber, carboxymethyl cellulose, a water reducing agent, a foaming agent, a foaming regulator, a catalyst, a crosslinking agent, a foam stabilizer, glyoxal and water. The heat preservation brick has the advantages of being excellent in heat preservation and insulation, sound insulation effect, compression resistance and the like, and is light in weight; a method for preparing the heat preservation brick does not need autoclaved curing, is low in equipment investment, simple in process, simple and convenient to operate, convenient to popularize, and stable in product quality.