The utility model provides a storage battery detection device of a direct current system. A processor of the device outputs a closing control signal according to an operation instruction to control closing of a relay, so a contactor is powered on, a normally-opened contact switch of the contactor is closed, the normally-closed contact switch of the contactor is opened, a storage battery and the normally-opened contact switch form a conductive circuit, the storage battery discharges. After discharging is over, the processor outputs an opening control signal according to an operation instruction to control opening of the relay, so the contactor is powered off, the normally-opened contact switch of the contactor is opened, the normally-closed contact switch of the contactor is closed, the storage battery and an alternating current power source of the direct current system form a conductive circuit, and the storage battery is charged by the alternating current power source. Charging and discharging of the storage battery are controlled without through manual operation, detection efficiency is improved.