EDTMP•Na5 is a neutral solid product. It is nitrogenous organic polyphosphonic acid, which is a part of cathodic corrosion inhibitor. This salt can be fully dissolved in water, innocuous and none pollution to environment, with good chemical stability and thermal tolerance. It has good scale inhibition property at temperature 200℃. EDTMP•Na5 can dissociate into 8 positive-negative ions, thus can chelate with more than two metal ions to form more than two polymer reticulation complex, the complex can be quickly dissolved in water to destroy the normal crystallization of calcium scale. It shows better scale inhibition effects to calcium sulfate and barium sulfate. EDTMP•Na5 can be used as scale and corrosion inhibitor for circulating water and boiler water system, chelating agent in non-cyanide electroplating, water-softening agent in dyeing industry, etc.