Abstract: One of the main reasons for corrosion of reinforced bars is the superfluous chlorine ion penetrating into the reinforced concrete. This article investigated and measured the reinforced concrete bridges, which had been put into use for 10 years along the seaside highway in Qinghuangdao area. The results show that there exist many damages, such as concrete cracks, reinforcement corrosion, and protection layer faking off. The measurement results show that the corrosion thickness of chlorine ion exceeds the thickness of protection layer in some places.