Wire beam electrode (WBE) was used to investigate the corrosion behavior of rebar for mortar with cracks of 0.1-0.3 mm, and the distribution of galvanic current and EIS on WBE were tested. Also, a reinforced concrete with the similar cracks was also exposed to marine splash zone for 700 d, the Nyquist figures were examined and the corrosion current density evolution was calculated. The results indicate that the passivation time of rebar protected by non-cracking concrete is 10-17 d, and the existence of cracks in concrete accelerates the oxygen migration and promotes the passivation of rebar. The passivation and corrosion of rebar for concrete is an uneven process from pit to surface. The cathode zone is formed near the cracks firstly because oxygen can migrate from cracks to rebar surface. Chloride ions transport from cracks to rebar surface, forming the massive anode zones. For the transverse crack size of less than 0.1 mm, the micro-cracks of concrete will be self-healing and decrease oxygen supply when concrete is exposed to marine tidal and splash zone for a long term, and the anode zones near cracks will transfer to cathode zones and delay corrosion of rebar. For the transverse crack size of more than 0.3 mm, the corrosion of rebar in crack zones will occur quickly and extend to both sides of crack, and the corrosion rate of rebar in concrete is 0.484 μm/a when it exposed to splash zone.