Used as the heavilizing agent of the second printing thin cotton, silk and the filling stuff of the wood products, and also for the manufacture of porcelain paint and material of protecting fire. In medicine, used as epsom salt. In microbial industry, used as the growth media, additives of brewing to be the nutrition sources of fermentation, to enhance the heat endurability as the filling agent in tanning industry, used as magnesium fat in agriculture and feed additives, in light industry, used in production of the fresh yeast MSG and the stabilizer of the calcium hydrogen phosphate for the toothpaste production, used as the congeal agents for cement, pulp and textile industry, and other industries.