The work aims to study the mechanized folding of the carton bottom with the bottom-locked carton as the study object. By analyzing the process requirements and technical principles of the bottom folding of bottom-locked carton, and discussing the key actuator’s design and layout of automatic folding device, the important mechanism was optimized with adams. The bottom folding of carton was achieved through the coordinated action of each actuator. The optimized mechanism greatly improved the dimensional folding flexibility of the carton. A reasonable mechanical folding process is formulated based on the traditional manual folding process and mechanical design theory, with which the automatic folding device is designed.