Abstract: Non-polluting sulfonitrocarburization (LT Process) has been established after the study of Z-1 regenerated salt, the preferred selection of process parameters, various examinations of properties and practice. The Z-1 regenerated salt possesses the quick- action and stability to adjust the content of molten bath. The LT treated workpieces made of different materials have good anti-wear, anti-friction, anti-seizure, anti-fatigue and anticorrosion properties. The process is charateristic not only of technology stability and extensive applicability, but also nonpollution to atmosphere and water. The LT process has produced and it will produce a great deal of economic and social results.