The invention discloses a grain storage method and a granary thereof. The method comprises the following steps that step 1, partial mulching and double-side suction type ventilation are adopted for reducing the grain moisture of the surface layer of a grain pile to 13%-14%; step 2, a matched control method is selected according to the external temperature for temperature control, so that the average grain temperature in the granary is in the range of 15-16 DEG C, and the average temperature of the granary is less than or equal to 22 DEG C; when the external temperature is 8-15 DEG C, full granary surface mulching can be formed, and a single-side draught fan is started to perform single-side suction type ventilation for the temperature control; when the external temperature is 15-25 DEG C,full granary surface mulching can be formed, and a grain surface gland method is adopted for the temperature control; when the external temperature is larger than 25 DEG C, full granary surface mulching can be formed, and a split type negative pressure grain cooler, an air conditioner and the single-side draught fan are started for the temperature control. The method is adopted for achieving the storage of the grain with the high moisture of 15-16%, reducing the water loss and maintaining the quality of the stored grain.