A battery management system and method. The battery management system manages a battery of a hybrid vehicle including a motor, a battery, and a main switch connecting the motor and the battery. The battery management system includes a sensing unit and an MCU. The sensing unit measures the current, the voltage and the temperature of the battery. The MCU integrates the battery current to produce an integrated current value, and determines whether the battery is overcharged or over discharged using the integrated current value.