The present invention discloses an orbicular sponge iron and the producing method used for treating water, which belongs to the metallurgy manufacturing technology region. The present invention is used for providing an orbicular sponge iron and the producing method used for treating water with appropriate grain diameter, high deoxidized iron content and much less iron crystal grain. The present invention is characterized in that: the grain diameter of the orbicular sponge iron is 1-5mm; the crystal grain is less than 10um, and the metal ratio is more than 90 percent. The preparation steps in the present invention consists of material-mixing, making sphere, oxidation sintering and direct deoxidization and so on. The present invention is developed according to the requirement for the zero-price iron material of the treated water; the method can develop an orbicular sponge iron, which can wipe off the deleterious and baneful infectant such as heavy metal, nitrate, and chlorine organic substance and so on in the water. Compared with the existing industrial sponge iron or other common zero-price iron material, the product is characterized in that the inner iron crystal grain is micron,the surface area is larger, the surface energy is higher, the deoxidization ability is stronger and the metal ratio is higher. The product is with some intensity, which can avoid the pulverization and hardening in the water treating process. The method and device of the present invention has the advantages of simple technical and low manufacturing cost.