The traditional models for VIVPEH (piezoelectric energy harvesting from vortex-induced vibration) are focused on a circular cylinder. In the present paper, a VIVPEH model was built to solve an aero-electromechanical coupling problem during VIVPEH with different cross-sectional shapes. The model was verified by a wind tunnel test. One key benefit of the present model is that the region from the initial position to the threshold of the lock-in region along the voltage time history curve can be calculated quite accurately compared with traditional methods. The present method will significantly contribute to the design and optimization of the key factors of VIVPEH, e.g., the bluff body shape and the electrical circuit.