Inherent to the influence of multiple factors, including environmental conditions and service time, prestressed steel strands corrode over time. This leads to concrete rust expansion and crackingand poses a critical threat to structural durability. To monitor the extent of cracking in this context, this study proposes a finite element simulation method based on piezoelectric wave propagation. Using Abaqus, a micro-scale model comprising mortar, aggregate, structural rebars, prestressed steel strands, and piezoelectric ceramics was constructed. By analyzing the electromechanical coupling process, concrete crack development induced by steel strand rust expansion was comprehensively monitored. The findings demonstrated that as corrosion progressed from the onset to mild stages, the piezoelectric signal-peak voltage increased by 13.4%, while the first wave reception time decreased by 1.2%. From the mild to accelerated corrosion stages, and up to the theoretical corrosion rate stage, influenced by corrosion-induced cracks, the peak voltage decreased, and the first wave reception time extended. Specifically, the voltage decreased by 6.6% and 48.6%, and first wave reception time increased by 6.0% and 29.8%, respectively. Based on the results of validation experiments, with discrepancies of less than 0.32 mV, the reliability of the proposed piezoelectric wave propagation method for monitoring prestressed concrete rust expansion using finite element models was confirmed.