Abstract: The 304 L stainless steel and 70 steel were treated by Si-Ca and Si-Ca-Ba alloys in laboratory and industrial test. The results of OM/SEM observations and tests for mechanical properties showed that the as-cast structure of the stainless steel treated by Si-Ca-Ba alloy is refined remarkably, and the lamellar thickness of pearlitic structure in 70 steel decreases with the pearlitic morphology showing clustering distribution because barium can change the surface energy of grains as a strong surface active element. Only a few bit of barium is found in steel and the enrichment of barium-bearing precipitated phase mostly lies on the grain boundary and phase boundary, thus improving the lattice misfit and preventing the movement of grain boundary and dislocation during heat-treatment and deformation. Therefore, the strength and toughness of barium-treated steels can be improved by the effects of intercrystalline strengthening and nail-prick dislocation.