A battery management system for a battery pack including a plurality of battery cells connected in series is provided. The battery management system includes a voltage divider, a plurality of switching units and a detection circuit. Each switching unit is corresponding to one of the battery cell and coupled between an anode of the corresponding battery cell and the voltage divider. When a control signal directs one of the switching units to turn on, the voltage divider divides a voltage difference transmitted from the one of the switching units to obtain a divided voltage signal, and transmits the divided voltage signal to the detection circuit, and the detection circuit detects the voltage difference according to the divided voltage signal, wherein the voltage difference is a voltage difference between an anode of the battery cell corresponding to the one of the switching units and a ground.