The work aims to realize the classification and stacking of different types of workpiece on automatic production line of packaging and stacking, and improve production efficiency and reduce production cost effectively. During the application of workpiece identification, a kind of sorting system based on machine vision, PLC control technology and HMI man-machine interface was proposed. Based on the design of the corresponding hardware and key algorithms of the industrial robot, the PLC network control system was built with Ethernet and the interaction with the upper management system was realized. According to the experimental test, the automatic sorting and stacking system had a high recognition accuracy of over 99% of the workpieces. The processing time was short, below 0.2 s, which could meet the production requirements. Production practice shows that the system has improved the sorting efficiency of workpiece, reduced labor intensity of workers and production costs, and it has very high application value.