Reinforcing concrete (RC) structures are applied extensively in civil engineering. The corrosion of RC steel, often called the cancer of the steel, however, deteriorates the durability of RC structures greatly and then degrades the serviceability severely. The usage of sensors in the RC corrosion monitoring is one potential method where two problems have to be carefully considered. First, the long-term power provision of sensor is very hard to be implemented in microsensor systems; second, the data delivery of corrosion monitoring ought not to impact the original structure where sensors are embedded. In this letter, we discuss and design a framework of energy-harvesting sensor network to monitor the steel corrosion in RC structure. Our framework provides insights about the corrosion-monitoring sensor system to store its ambient energy, and about effectively exploiting wireless sensor network to deliver the corrosion data to the end user.