SDFe55 alloy coating with high hardness (850 HV0.2) is prepared on the surface of piston by laser cladding. The structure, composition and corrosion resistance are studied by means of scanning electron microscope (SEM), X-ray diffraction (XRD), electron probe micro analysis (EPMA) and corrosion testing. The results show that laser cladding Fe-based coating is uniform without cracks and pores, has metallurgical bonding with the matrix, and is composed by γ(Fe, Ni) and carbides of type M23C6 . The corrosion resistance is higher than that of 45# steel due to combined effects of formation of austenite structure and refined dendrites, as well as disperse distribution of carbides. Moreover, composition distribution in the laser cladding layer is average, and the content of Fe element at the grain boundary is lower, and those of Cr, Mo elements at the boundary are higher than inside grain, while Ni element distributes homogeneously in the whole layer, which is beneficial to the improvement of ductility and corrosion resistance.