With the rapid development of renewable energy，molten salt phase change heat storage technology has received high attention.Stable phase change heat storage materials composed of ceramics and molten salt have the advantages of large heat storage，simple process，and low cost，thus gradually becoming a research hotspot.However，due to the high hygroscopicity of molten salt，there is a problem of phase change latent heat attenuation caused by the loss of molten salt in the humidity environment of molten salt/ceramic phase change composite thermal storage materials.The surface of K₂CO₃-Na₂CO₃/MgO/glass phase change composite heat storage material was treated by encapsulating agent embedding and firing into a film，forming an insoluble coating on its surface，which solved the problem of molten salt leakage of phase change composite heat storage materials in high humidity environments.The results of humidity test showed that the latent heat of phase change of the unencapsulated materials was decreased from 58 J/g to 28 J/g，and the salt absorption weight of cellophane at the bottom of the materials was increased by 1.32 g.The phase change latent heat of the encapsulated materials was decreased from 55 J/g to 53 J/g，and the salt absorption weight of cellophane at the bottom of the materials was increased by 0.12 g.Compared with unencapsulated materials，the phase change latent heat decay rate of the encapsulated materials was decreased from 51.72% to 3.63%，and the leakage of molten salt was significantly reduced，which could effectively solve the problem of molten salt leakage caused by high humidity and further expand the application range of the materials.