The invention relates to a robot destacking system and discloses a robot system having a turnover box recognizing function and a recognition method thereof. The robot system comprises a turnover box conveying line, a robot and a clamp, wherein the robot is located on the side of the turnover box conveying line, and the clamp is connected onto a mechanical arm of the robot. A scanner for recognizing position coordinates of turnover boxes is installed on the side of the clamp, four probe devices are installed at the bottom of the clamp, and a plurality of grooves are arranged on the turnover boxes corresponding to the probe device and used for the probe devices to probe the forward and reverse directions and/or the heights of the turnover boxes. The probe devices are added in the robot clamp, so that the robot system can recognize the specific positions of the turnover boxes and judge the sizes, the models and the forward and reverse directions of the turnover boxes.