The invention relates to building materials, in particular to a heat reserving brick. The heat reserving brick is composed of a heat reserving core layer, a phase change layer and a fire protection layer wrapped on the surface of the phase change layer. A manufacture method includes the following steps that raw materials of the heat reserving layer are molded in a pressed mode, the phase change layer is wrapped on the surface of the heat reserving core layer, and the phase change layer and the heat reserving core layer are molded in a sintered mode. The precast fire protection layer is seamed together with the phase change layer. In the heat reserving brick, through combination of the heat reserving core layer, the phase layer and the fire protection layer, the heat reserving effect of the brick is improved, heat regulating efficiency is achieved, and a sound absorbing effect and a light-quality effect are also achieved. In addition, environment pressure is relieved by using slag and papermaking sludge as raw materials.