An inorganic phase change energy storage particle, floor heating mortar and a preparation method thereof, wherein the mass percentage composition of the inorganic phase change energy storage particle includes: 20%-50% inorganic phase change material, 10%-25% water, 0.1%-1.5% Phosphated starch glue, 0.1%-1.5% water-absorbing resin, 10%-35% gypsum and 15%-35% cement; prepared phosphated starch glue, ingredients, mixing, granulation and coating, and coating The ground heating mortar is composed of 15% to 35% cement, 10% to 25% sand, 20% to 50% inorganic phase change energy storage particles, and 20% to 30% water; it is prepared by batching and mixing. The invention has wide sources of raw materials, good chemical stability, low phase transition temperature, no leakage, good energy storage effect of energy storage particles, high stability, high strength of floor heating mortar, can effectively adjust indoor temperature, good energy saving effect, and can be widely used It is widely used in residential buildings, schools, hospitals and other buildings.