The invention relates to a foam glass ceramic prepared from blast furnace hot melting slag and a preparation method of the foam glass ceramic, belonging to the field of inorganic materials. In the preparation method, steeling blast furnace hot melting slag is used as a main raw material, coal ash, borax, calcined soda, rear sorted tail ore, quartz sand and the like are respectively measured, evenly mixed and then baked into porous blocks, the porous blocks are added in a slag ladle, smelting is carried out by using the blast furnace hot melting slag, a melting material is subject to water quenching to obtain glass water quenching materials with different particle sizes; and the glass water quenching materials are dried and ball-milled, a foaming agent is added to be mixed with the dried and ball-milled glass water quenching materials, press forming or spreading forming is carried out, and then the foam glass ceramic is prepared by nucleating, crystallization and sintering. In the invention, a large amount of heat energy stored in the blast furnace hot melting slag is effectively utilized, and production cost is lowered; and the prepared foam glass ceramic has the characteristics of low thermal conductivity, small density, high temperature resistance, corrosion resistance and high compression resistance and breaking strength, has strong adaptable property on high-low temperature variation of smoke, and can be widely used as a multi-cylinder type and sleeve type lining material for discharging smoke by wet desulphurization in a heat-engine plant, thermal equipment insulation, heat-insulating materials and the like.