A balanced charging/discharging circuit for a lithium battery set, including a plurality of serially connected lithium batteries each having a positive electrode controlled by a corresponding control signal to selectively establish connection with a positive electrode of a battery charging circuit, and a negative electrode controlled by a corresponding control signal to selectively establish connection with a negative electrode of the battery charging circuit. Voltage of the positive and negative electrodes of each of the serially connected lithium batteries is transmitted to a corresponding terminal of a control circuit respectively so that the control circuit generates a corresponding transfer signal to the battery charging circuit and supplies the control signal to establish connection of a corresponding series of lithium batteries for charging. Battery sets arranged in series or in parallel can be charged with the maximum current and the service life is extended and charging time is shortened.