The invention discloses a cooling granule for reducing the temperature of smoke gas of heated unburned cigarette, and a preparation method thereof. The cooling granule is prepared from raw materials,that is, a low-temperature decomposition compound, a base material and a binder, through the wet granulation technology. The cooling granule disclosed by the invention cools the smoke gas by using thedecomposition heat absorption characteristics of the low-temperature decomposition compound, if the cooling granule is added to a cigarette product, the cooling granule generates no thermal deformation after being heated, the granules are not bonded to each other, so that the circulation of the smoke gas is not blocked, the decomposition products do not affect the quality of the smoke gas, furthermore, the raw materials are easily available, the price is low, the preparation method is simple, and the industrial production is realized easily.