The invention discloses a solid composite phase-change thermal storage material, belonging to the technical field of energy storage materials. The solid composite phase-change thermal storage material comprises water, sodium carbonate, potassium carbonate, magnesium oxide, kieselguhr, quartz sand and kaolin. The thermal storage material is non-toxic, harmless and free of pollution. The invention further discloses a preparation method of the solid composite phase-change thermal storage material. The preparation method comprises the following steps: stirring, rubbing sand, filtering, performing hydraulic molding, and performing sintering molding. By adopting the preparation method, the thermal storage density is improved, the thermal storage density of the material is 2 times better than that of a common material, the thermal storage material can endure high temperature, can be heated to be greater than 650 DEG C, and is not liable to efflorescence when being used for a long time.