<p>Vibration energy harvesting technology, with its ability to continuously supply power without needing an external power source, has become an essential solution for powering low-power devices. To address the power supply issue for low-power sensors and satisfy the requirement for energy harvesting in rotating situations, this paper utilizes a magnetostrictive material (Fe-Ga alloy) to design a double-beam spinning energy harvesting device that is spring-coupled and magnetically adjustable. A systematic dynamic model and magnetic dipole model were established, and the control equations for the system were ultimately derived. Furthermore, a thorough theoretical and experimental analysis was conducted to determine how the pre-magnetization field arrangement, magnet spacing, and spring stiffness affected the device’s output performance. According to the experimental findings, the energy harvester may produce two output voltages when exposed to the same rotational excitation. The optimized energy harvester can reach a maximum power of 291.6 µW and a peak output voltage of 350 mV. The proposed energy harvester broadens the collection bandwidth and shows potential in low-frequency environments, providing a theoretical reference for developing micro-power self-powered devices in rotating mechanical systems.</p>