For the purpose of exploring the failure characteristics of urban concrete bridge under deicing salt scaling and evaluating the existing structure condition, main physical and mechanical properties of the material, chloride ion concentration distribution, and the microstructure of concrete cover and corroded steel bar were studied through site investigation, sampling and laboratory experiments. The results show that serious salt freezing damage and steel bar corrosion occur in the main structure of the bridge, when the bridge has been used under deicing salt scaling for 13 years. Chloride ion binding capacity of concrete is quite weak; meanwhile, free chloride ion concentration is very high. The products from bar corrosion adsorb a large amount of chloride ions physically. Microstructure analysis indicates that chloride ions migrate to the interface of rebar and concrete, and its total chlorine concentration is almost twice that in other location, such as surface or interface of steel bars. The distribution behavior of chloride ion concentration of concrete cover does not fit the Ficks second diffusion law. Therefore, durability design of bridge structures under deicing salt scaling needs to improve salt freezing resistance and chloride ion permeability, moreover, surface effects must be taken into account in the chloride diffusion model when life design is carried on.