The invention relates to a type-III deep bed type iodine adsorber, which comprises an iodine adsorber chamber. A plurality of carbon beds are arranged in the iodine adsorber chamber, the top of the iodine adsorber chamber is provided with a loading system communicated with the carbon beds, the bottom of the iodine adsorber chamber is provided with an unloading system communicated with the carbon beds, lateral sides of the iodine adsorber chamber are provided with an activated carbon sampling system and a differential pressure measuring system, and two sides of the iodine adsorber chamber are provided with an air inlet and an air outlet respectively. Each carbon bed is rhombic and comprises two screen plates and non-perforated frames around the screen plates, the non-perforated frames of the carbon beds are hermetically connected with inner walls of the iodine adsorber chamber, the screen plates are provided with through holes, and a gap is reserved between every two adjacent carbon beds and forms a gas guide passage. Activated carbon in the carbon beds can be utilized effectively, and radioactive wastes are reduced on the premise of purification efficiency improvement.