Abstract: Under the service environment, because of chemical and electro-chemical reactions between the surrounding medium and the material elements, local corrosions are easy to form on the surface of metal. The corrosion damage will degrade the useful properties of materials and weaken the strength of the structures. In order to better understand the local corrosion damage degradation process, a numerical model based on the cellular automata method for the three-dimensional simulation of the metal corrosion damage is developed In a mesoscopic scale, the single-pit corrosion and the multi-pit corrosion on the surfaces of metal are simulated under different electrolyte concentrations and temperatures. The result provides a theoretical reference for studying the degradation mechanism of metal structures under the service environment.