Thiourea Dioxide (TDO) is a new kind of reducing agent that used as exchange of sodium hydrosulfite. It is widely used in textile and paper making industry. This product is also used in leather processing industry, paper, pulp and board industry, photographic industry, bleaching and reducing agents. This product is also a component of decolorisation agents. In macromolecule material industry, it is used as catalysis agent and stabilizer of resinic producing, and it is also used in organic synthesization of sensitizing material, and medicine, medical, spicery materials in fine chemicals, and also can be applied in the recycling and separating of heavy metals.