Disclosed are system and method for adjusting a voltage balancing of cell in a lithium ion multicell battery pack, the system comprising; a multicell battery pack including a master module and a slave module, a CPU located in the system controller and outputting a synchronization signal for each of the cells in the master module and the slave module, a first vertical interface transmitting the synchronization signal outputted from the CPU to the master module, and a second vertical interface transmitting the synchronization signal to the slave module through the first vertical interface.