<p>In this study, advanced material analysis methods were employed. These methods included electron backscatter diffraction, energy-dispersive spectroscopy analysis, and x-ray diffraction. They were used to investigate the microstructure, phase composition, and interface characteristics of the transition layer weld, substrate, and cladding material in the stainless steel/low-alloy high-strength steel composite material, and to explore how this interface was formed. The research results show that chromium diffuses from the cladding material to the substrate, while iron and carbon diffuse from the substrate to the cladding material, at the interface, a decarburization layers, carburized layers and austenite band were formed. As the welding line energy of the transition layer weld increases, the stress at the interface of the transition layer weld/substrate/cladding material increases, the driving force for atomic diffusion increases, the distance of carbon atom diffusion in the substrate area increases, the width of the coarse ferrite area becomes wider, and the hardness decreases. At the same time, it increases the aggregation of carbon and chromium atoms on the interface of the cladding material side. When the line energy reaches 22.4&#xa0;KJ/mm, martensite forms on the overlay side of the interface, and the microhardness increases. Meanwhile, in the interface zone, grains form texture along the direction of atomic diffusion, and the peak texture strength is 3.150 in the direction. When the interface between the transition layer weld and cladding layer weld is higher than that of the composite material, it helps to improve the tensile properties of the joint. The corrosion resistance of the joint is mainly determined by the welding heat input of the cladding layer weld.</p>