The invention discloses an autonomous charging system and method for a mobile routing inspection polar robot and belongs to the robot field. The system includes a polar robot body, a charging bin body provided with an entrance and an exit, and ramps which are correspondingly arranged at side edges of the entrance and the exit. According to the autonomous charging system and method of the invention, an image recognition-based autonomous charging scheme is adopted; in the installation and debugging process of the system, a plurality of target objects are installed at an application site; the target objects are characterized by easiness in recognition and no possibility of being confused according to the environment of the site and an image recognition algorithm; the robot, based on program setting, successively searches the target objects through camera image recognition, and approaches the entrance of the charging bin from far to near; at the entrance of the charging bin, included angles between the target objects and the robot body are calculated, so that the pose of the robot is adjusted, and therefore, the robot can be aligned with the entrance of the charging bin; when the robot enters the charging bin, the pose of the robot is adjusted, so that the robot can be aligned with the charging bin; and when detecting that the robot successfully docks with a charging interface, the robot stops immediately.