For the automated access process of intelligent warehouse materials, for the access of materials stored in cartons, it is necessary to carry out tasks such as carton size measurement, carton disassembly, material dumping, material picking, etc. Therefore, the carton should firstly be unmanned size measurement, and the SGBM improvement algorithm of Adaptive GrabCut is proposed to realize the automatic measurement of carton size. The method firstly completes the calibration of binocular camera, uses NLM algorithm to denoise the collected pictures, completes the stereo correction of carton pictures, uses NCC, SGBM, AD-Census three stereo matching algorithms to get the parallax map of carton, on the basis of analyzing the effect, proposes the SGBM improvement algorithm based on the template matching Adaptive GrabCut to be used for the stereo matching of carton and get its size information. The experimental results show that the improved algorithm can realize the accurate measurement of carton size information, and the size error is less than 10 mm, which meets the actual production requirements.