This document specifies the requirements, test methods, inspection rules, marking and accompanying documents, packaging, transportation and storage of magnesium chloride hexahydrate, a by-product of the format reaction. This document is applicable to the magnesium chloride aqueous solution produced by the Grignard reaction during the production of p-hydroxyphenylethyl alcohol and 2-cyano-4'-methylbiphenyl (sartanbiphenyl), after extraction, decolorization, concentration and slicing, etc. The obtained magnesium chloride hexahydrate is mainly used as building materials, snow melting agent, etc.