Both electric vehicles and energy storage systems need to use a large number of batteries, and the current research on batteries is quite diverse. This study presents a modular high-frequency multi-winding battery cell equalizer for a large number of batteries. In order to increase the power density of the circuit and reduce the size, the switching frequency is increased by using parasitic elements to participate in resonance. Increasing the switching frequency to lMHz, and adding a resonant network to achieve soft switching and reduce switch stress for the converter. The proposed multi-winding design allows battery equalization from any cell to any cell, and the modular architecture can improve the flexibility of the converter. This research uses POWER SIM circuit simulation software to investigate the feasibility of the proposed battery equalizer.