In reinforced concrete structures, corrosion of the rebar produces 2–6 times more corrosion product than the original material, creating pressure on the surrounding concrete, leading to cracking. The study of corrosion and cracking in reinforced concrete structures is therefore of great importance for enhancing the durability of concrete. Unlike many previous studies, we used ribbed rebar similar to that used commercially and considered the mechanical behavior of the interface transition zone (ITZ) between the aggregate and mortar to simulate the processes of corrosion and cracking of reinforced concrete structures. We explored the failure mode of the interface layer under uniform corrosion and the influence of different factors on the corro-sion expansion cracking and the shedding mode of a concrete cover. This was achieved by establishing a three-phase meso-scale model of concrete based on secondary development of ABAQUS, simulating the mechanical behavior of the ITZ using a cohe-sive element, and establishing a rust expansion cracking model for single and multiple rebars. The results showed that: (1) Under uniform rust expansion, concrete cracks are distributed in a cross pattern with a slightly shorter lower limb. (2) When the corro-sion rate is low, the ITZ is not damaged. With an increase in the corrosion rate, the proportion of elements with tensile damage in the ITZ first increases and then decreases. (3) In the case of a single rebar, the larger the cover thickness, the higher the corrosion rate corresponding to ITZ failure, and the arrangement of the rebar has little influence on the ITZ failure mode. (4) In the case of multiple rebars, the concrete cover cracks when the rebar spacing is small, and wedge-shaped spalling occurs when the spacing is large.