Melting and crystallization of non-metallic inclusions in contact with steel matrix during laser treatment was investigated. It was shown that laser action is the method of local change of inclusion structure in the surface fused layers and also of the properties of non-metallic inclusion surface. Peculiarities of steel matrix saturation with elements of non-metallic inclusions during different regimes of laser action were investigated. It was shown the role of that process in the formation of local structure of steel matrix near non-metallic inclusions. That allows to realize possibility of transformation of the non-metallic inclusions how sources of inside local alloying of steel matrix. It was fixed that in local areas of steel matrix the liquation strengthened zones were formed. They represent different types of composite layers: gradiental zones with cascade and “spot” distribution of elements and nanohardness, dispersal zones with different types of microphases and nanophases, “tunnel” zones, and also zones with combine structure. It was shown the role of non-metallic inclusions in development of micro heterogeneous strengthening of steels under laser treatment.