Sodium Tripolyphosphate, Na5P3O10, Molecular weight 367.86, white powder; Melting point 622 °C. free soluble in water, aqueous solution appears acid. It has got salient chelating capacity to metal ions of Ca and Mg etc. and can soften hard water to make suspension into solution, alkalinity, without causticity. It is an inorganic compound with formula Na5P3O10, is the sodium salt of the polyphosphate penta-anion, which is the conjugate base of triphosphoric acid.Sodium tripolyphosphate is produced by heating stoichiometric mixture of disodium phosphate, Na2HPO4, and monosodium phosphate, NaH2PO4, under carefully controlled conditions. It has different bulk density, i.e. low density 0.35-0.6g/cm 3 , medium density 0.6-0.8g/cm3 and high density 0.8-1.0g/cm3. This product has two crystalline forms, namely phase I (high temperature phase) and phase II (low temperature phase). The chemical properties of the two phases are the same, and the difference between them lies in the thermostability, hygroscopicity, solubility and hydration heat when dissolving. It can be used as one of the main auxiliaries for synthetic detergent, synergist for soap; water softener, tanning agent for leather making, auxiliary for dyeing; As an effective dispersion agent for suspensions of coatings, kaolin, magnesium oxide, calcium carbonate and drilling mud etc. As an oil contamination resistance agent in paper production; As in foodstuff industry it is used as quality improver in the process of canned food, fruit juice drinks, foodstuffs from milk or soybeans. It may tender the meat in canned ham and soften the skin of horse bean in canned horse bean. It may also serves as a softener or densifier in foodstuff industry.