The invention discloses an agricultural drying system and a drying process thereof. The modes of circular air supply and automatic moisture removal are adopted for material drying, so that the heat utilization ratio and the degree of automation are both high. The agricultural drying system comprises a heating chamber and a drying chamber between which a partition wall is arranged, wherein a combustion furnace is mounted in the heating chamber; intake fans and return fans are mounted on the partition wall; first one-way opening window blinds and second one-way opening window blinds are arranged on the partition wall and correspond to the intake fans and the return fans; a pressure regulating and moisture removing air inlet door which can be opened and closed is arranged on the heating chamber; third one-way opening window blinds and an open door used for material loading and unloading are arranged on the side wall of the drying chamber; and the third one-way opening window blinds are used for enabling air to flow outdoors in one direction from the drying chamber under the action of pressure difference.