MgCl2•nH2O,n<6).Inordertoimprovethequalityofproduct(MgCl2 or MgCl2•nH2O),afewbetterproposalsofimproveddehydrationtechnologyareproposed.In dehydrationprocess,manyfactorsshouldbetakenintoconsideration,suchaseconomicbenefits, productionefficiency,environmentalproblems,purity.