The utility model relates to a storage battery voltage balancing device belonging to a charge-discharge intelligent control device for a storage battery set used in power system direct-current power source. A storage battery charge control circuit is connected to a single-chip microcomputer; a storage battery management chip is connected with the single-chip microcomputer through an SPI bus. In a storage battery voltage acquisition circuit, a plurality of storage batteries connected in series form a storage battery set. The positive electrode of each storage battery in the storage battery set is connected with the storage battery management chip. In a storage battery discharge control circuit, the positive electrode of each storage battery is connected with a source D of a P-type MOSFET. The negative electrode of the storage battery is connected with a discharge resistor in series, and is connected with a drain S of the P-type MOSFET. A gate G of the P-type MOSFET is connected with the storage battery management chip. During discharging, only the overcharged battery is discharged; and during charging, only the battery with low capacity is charged. The device provided by the utility model has the characteristics of small volume, low noise, high reliability, and real-time control.