The utility model discloses a battery performance detection device and DC power supply system, DC power supply system include power supply loop and battery performance detection device, and power supply loop is including the NULL module, AC distribution module, rectifier module, storage battery, the dc bus that connect gradually, and its battery performance detection device includes rectification monitoring module, battery monitoring module, the module of discharging, direct current monitoring module, rectification monitoring module is connected with the DC power supply system rectifier module output, battery monitoring module and storage battery feeding end connection, the module of discharging and the storage battery loop connection that discharges, rectification monitoring module, battery monitoring module, the module of discharging are connected with the direct current monitoring module respectively. The utility model provides a DC power supply system can not in time reflect the true situation of storage battery performance, the battery performance detects and the capacity detects the problem that relies on manual operation.