The utility model discloses an adapter for a single main material and double main materials of an iron tower. The adapter for the single main material and the double main materials of the iron tower comprises a base plate, an upper cross connecting plate and a lower cross connecting plate, wherein the base plate comprises an upper surface and a lower surface, the upper cross connecting plate is connected with the single main material of the iron tower, and is arranged on the upper surface of the base plate, the lower cross connecting plate is connected with the double main materials of the iron tower, and is arranged on the lower surface of the base plate, and the cross center of the lower cross connecting plate does not align to the cross center of the upper cross connecting plate. Due to the fact that the upper cross connecting plate and the lower cross connecting plate are arranged on the base plate in the mode that the cross center of the upper cross connecting plate does not align to the cross center of the lower cross connecting plate, the center of the single main material and the centers of the double main materials can be in alignment by adjusting the position of the upper cross connecting plate and the position of the lower cross connecting plate in the manufacturing process of the adapter, and the eccentricity phenomenon is avoided; the load is transmitted from the single main material to the base plate, then the load is evenly transmitted to the double main materials according to rigidity of the base plate, the purpose that even distribution of the load is achieved through the base plate, and stability of the iron tower is improved. The utility model further discloses the iron tower.