A characteristic tracking method for a battery module including at least one battery is disclosed. A look-up table is provided according to a primary characteristic of the battery. It is determined whether a battery has satisfied a preset condition when the battery module is operated from a usage state to an idling state. The battery is measured to have obtained a first voltage and a real capacity when the battery satisfies the preset condition. The measured first voltage is utilized to locate a table capacity of the battery from the look-up table. The look-up table is updated according to the real capacity and the table capacity. A peripheral circuit of characteristic tracking method has been exhibited.