The invention discloses a portable DC system battery pack with the self-checking capability, and the battery pack comprises a housing, and a battery pack formed by the connection of a plurality of batteries is arranged in the housing. A positive electrode column and a negative electrode column are arranged on the battery pack. A top cover is arranged at the top of the housing, and a fixing plate for fixing the battery pack is arranged at the bottom of the top cover. A first mounting cavity is formed at the upper part of the housing, and a battery internal resistance detection circuit is arranged in the first mounting cavity. The battery internal resistance detection circuit is connected with a plurality of battery voltage sampling units used for sampling a battery voltage and a plurality of battery current acquisition units used for sampling a battery voltage. A display screen is embedded at the top of the first installation cavity, and the battery internal resistance detection circuitis connected with the display screen through a display circuit. The internal resistance of the battery is detected in real time, so that the state of the battery can be known in time.