Modified sodium disilicate (MSD), with molecular formula of Na2Si2O5 and commercial designation of MDS, is manufactured through special process of adding active auxiliaries into sodium silicate. The pH value is within 10.5 – 12.5, apparent density within 0.2—0.7g/cm3. Besides, it’s characterized by fast dissolving speed, lower requirement for temperature and better solubility than crystalline layered sodium disilicate, 4A zeolite and other sodium silicate powder products. As a phosphorous-free detergent auxiliary, the modified sodium disilicate (MDS) satisfies all technical and ecological requirements for substitute of STPP.