The invention discloses a balance management module for a series battery pack for power supply inside an instrument. The balance management module is composed of a detection protecting unit, a charging unit, a control unit and a balancing unit, wherein the detection protecting unit and the balancing unit are used for feeding back the quantity and parameters of the connected monomer batteries; the control unit is used for selecting a charging mode of the charging unit according to the magnitude of a feedback signal of charging current detection and guaranteeing the voltage of each monomer battery in the balancing state in the charging and discharging processes; the control unit is equipped with anti-reverse protection for external voltage input and battery connection and charging over-current protection. The control unit adopted by the balance management module is used for detecting, intelligently deciding and controlling the charging process and performing balance management on the voltage of each monomer battery in the charging and discharging processes, an electrolytic capacitor is used as a balance energy transfer carrier and a decoder is used for controlling the selection for the to-be-balanced monomer battery, so that on the basis of realizing the safe, efficient and balancing charging and discharging, the related parameters of the built-in series battery pack can be supplied to the instrument simultaneously. The balance management module is suitable for the balance management of the series battery pack for power supply inside 2-8S instrument.