With an increasing concern for remaining service-life of cracked concrete structures exposed to marine or de-icing environment, chloride transport and rebar corrosion in cracked concrete are becoming more important topics. Crack depth has a direct relationship with chloride transport and rebar de-passivation in cracked concrete. However, the influence of crack depth on chloride transport in concrete is little reported by literatures. The present research conducted experimental research on the influence of crack depth on natural chloride diffusion in concrete at transient condition. Crack patterns, chloride profiles, surface chloride contents and diffusion coefficients are adopted to study the influence of crack depth on chloride transport in concrete. The experimental results show that concentrations of water or acid soluble chloride from different grinding layers (the thickness of each layer is approximately 2 mm) increased with increasing crack depth until it reaching 15 mm. In general, the chloride diffusivity grown with increasing crack depth from 0 mm to 25 mm. Relationships between diffusion coefficient and crack depth can be separately described as linear (acid soluble chloride) and exponential (water soluble chloride) functions.