Abstract: Clarifying the mechanical properties of reinforcement corrosion products in marine environments is of great significance for establishing corrosion-induced expansion and cracking models. Relies on the field observation research base of long-term performance of marine infrastructure for transportation industry, the sampling and analysis of reinforcement corrosion products from steel plates and embedded reinforced concrete exposed to marine environments for 15 years, as well as the corrosion-induced expansion and cracking concrete beam components of a pier in Wenzhou were carried out. The nanoindentation elastic modulus, hardness and instantaneous elastic modulus of the corrosion products were characterized through nanoindentation and consolidation tests, and the microstructure and composition were analyzed. The results show that the elastic modulus of corrosion products on steel plate was lower than that of steel corrosion products in concrete. The elastic modulus of steel corrosion products was concentrated in the range of 70-110 GPa, and the hardness was in the range of 0.002-0.013 GPa. Based on the Hertz elastic contact theory, the instantaneous elastic modulus of steel corrosion products was concentrated in the range of 100-150 GPa. The microstructure of steel corrosion products in concrete was relatively dense, and the atomic ratio of Fe and O in different corrosion products was quite different, and the proportion of corrosion components was different. At the same time, a certain proportion of Cl elements was tested, indicating that steel corrosion was closely related to the erosion of Cl^-.