The embodiment of the invention discloses a protection device for a DC power distribution network and a protection method thereof. The DC power distribution network comprises at least two power distribution sub-networks and at least one bus connecting line, wherein any power distribution sub-network comprises an incoming line, at least one bus and at least one feeder line, the incoming line is electrically connected with the at least one bus, the at least one bus is electrically connected with the at least one feeder line, and the two ends of any bus connecting line are electrically connectedwith the buses in the two power distribution sub-networks respectively. The protection device for the DC power distribution network comprises at least one current limiter, any one current limiter is arranged on a corresponding bus connecting line, and any one current limiter is used for entering a current limiting mode when the current on the corresponding bus connecting line is greater than or equal to a first preset current so as to limit the current on the corresponding bus connecting line. According to the technical scheme of the embodiment of the invention, the fault side and the non-fault side of the DC power distribution network can be isolated, and the fault side can conveniently remove faults.