A phase-change heat-storage foamed concrete, and a preparation method and use thereof are provided. The phase-change heat-storage foamed concrete provided by the present disclosure is prepared from raw materials including, in percentages by mass: 50-70% of a cement, 2-20% of a supported phase-change material, 15-35% of water, 0.1-0.5% of a water-reducing agent, 0.5-1.5% of a foam stabilizing agent, 0.5-2% of an aqueous hydrogen peroxide solution, and 0.1-0.4% of a hydrogen peroxide decomposition catalyst. The supported phase-change material includes an acid-modified fly ash and a paraffin supported on a surface and in a pore structure of the acid-modified fly ash, and the aqueous hydrogen peroxide solution has a mass percentage concentration of 25-30%.