Abstract: New technology for production of sodium tripolyphosphate (STPP) with chemical purification measure was studied.In this process,the raw material wet-process phosphoric acid (WAP) was neutralized by ammonia gas to obtain ammonium dihydrogen phosphate solution lower in impurities;and then sodium carbonate was added to obtain pure mono-sodium dihydrogen phosphate crystals,which was polymerized with sodium carbonate directly at high temperature to produce high quality STPP.Through experiments,the optimal technological conditions of preparing high quality STPP were obtained.The product was of the highest quality of 97.81％ under the optimal conditions,which conformed to the best-grade in Standard of Industrial STPP,GB 9983—1988.