A direct current power supply system includes N power supply devices, N triple-pole direct current switches, a positive bus, an M bus, and a negative bus. A positive input terminal of an ith triple-pole direct current switch is coupled to a first output terminal of an ith power supply device, an M input terminal of the ith triple-pole direct current switch is coupled to a second output terminal of the ith power supply device, a negative input terminal of the ith triple-pole direct current switch is coupled to a third output terminal of the ith power supply device, a positive output terminal of the ith triple-pole direct current switch is coupled to the positive bus, an M input terminal of the ith triple-pole direct current switch is coupled to the M bus, and a negative output terminal of the ith triple-pole direct current switch is coupled to the negative bus.