Abstract: Two new processes for the production of insoluble sulfur (IS) were studied in thispaper.One is low temperature polymerization process of sulfur at temperature less than 350℃ and under atmospheric pressure in the presence of catalyst promotor system,aiming at producing medium grade IS.Another is mixed solvent extraction process with a small amount of additive for the production of higher grade IS.In comparison with the old high temperature polymerization and single solvent (carbon disulfide) extraction processes respectively,these two new processes are lower in first cost and operation/maintainance cost,less energy consumption and safe in operation.