The invention relates to the technical field of a heating tail end device, in particular to a composite phase change material, a preparation method of the composite phase change material, energy storage slurry and an energy storage floor board. The composite phase change material comprises an organic phase change material and an inorganic carrier, wherein the organic phase change material is fully filled in pores of the inorganic carrier, and is polyethylene glycol; the inorganic carrier is expanded graphite; the mass ratio of the polyethylene glycol to the expanded graphite is 11.5:1. The composite phase change material provided by the invention uses the polyethylene glycol as the phase change material, and uses the expanded graphite as a support and enhancing heat transfer material. The polyethylene glycol and the expanded graphite are subjected to negative pressure adsorption for 10 min in a constant temperature drying box at the pressure being -0.05 Mpa and the temperature being 70 DEG C according to a mass ratio of 11.5:1 to obtain the composite phase change material. The expanded graphite has the advantages that the heat conduction coefficient is high; the developed reticular hole type structures are realized; through the capillary effects of the micropores, the phase change material of the polyethylene glycol is adsorbed into the micropores, so that the leakage of the liquid-state phase change material is effectively avoided; the heat conduction performance of the phase change material is improved; meanwhile, the volume is basically unchanged in the phase change process.