Addressing the issue of energy inconsistency in series-connected lithium-ion battery packs, this paper proposes a multi-level modular equalization system based on a multi-port CLLC converter topology. Within the equalizer, the cell-level sub-modules achieve parallel energy balancing among individual battery cells. The energy balancing paths between cells within each sub-module operate independently, ensuring that the balancing speed is unaffected by the number of series-connected batteries. At the module level, the internal balancing units collaborate with the energy transfer unit to enable multi-path energy balancing across battery modules, significantly increasing both the number of simultaneously balanced targets and the overall balancing speed. Furthermore, the proposed balancing module topology enables transformer multiplexing while achieving Zero-Voltage Switching (ZVS) for the semiconductor devices, thereby effectively reducing circuit switching losses. Finally, to validate the effectiveness and advantages of the proposed equalizer, we conducted detailed operational principle analysis, and constructed an experimental platform comprising twelve serially connected battery cells. Experimental results demonstrate the superiority of the proposed equalizer.