Abstract: This paper introduces the recent development in the study and applications of the in-situ monitoring of concrete structures in marine environment. The author discusses the concept, theory and function of the monitoring of concrete structures, the first European generation of pre-embedded anode ladder of concrete structure durability and its system as well as the expansion ring anode and its system. More importantly, the paper includes the second generation of the durability monitoring techniques developed with international partners, based on the electrochemical principles and the optical fiber aided technology. The paper also discusses the personalized diagnostic criteria of corrosion after depassivation of different parts of the steel bar, the minimally invasive intervention, and the precondition of postposition. Practical results show that the consistent monitoring of the corrosion status of steel bar in concrete structures is a feasible measure in durability design, which ensures the life expectancy of basic facilities. Moreover, the durability information obtained from in-situ concrete might be applied to the residual life prediction of a structure.