The corrosion damage of reinforced concrete balustrades of LianYun-Harbor west dam is investigated by on-site and lab testing. The contents of investigation include outlook-check on site, un-damaged test, and lab-test of on-site samples. It shows as follow: Cl- penetration is the direct reason of concrete corrosion damage under marine environment, and poor construction quality is the main reason. At the same time the primary design is not reasonable. Reinforcement corrosion in concrete is the synthetic effect of environment, construction and design. Now, the corrosion has threatened the normal function of balustrade structure and the balustrade structure needs repair and rehabilitation.