Investigation shows that concrete corrosion is a common problem for ocean reinforced concrete (R.C.) structures along China’s coast. A discussion of the corrosion characteristics, based on real project cases and field surveys, is presented in this paper. These factors that might affect corrosion, such as environmental effects, construction quality, cover thickness, property of the concrete material and structure type, are evaluated. Based on the analysis of these corrosion characteristics and affecting factors, the approaches available to improve the durability of ocean R.C. structures are proposed.