To design an automatic control system for sorting smoke boxes based on the production practice, in order to solve the problems of high labor-intensity, low efficiency, high error rate and other issues in the manual sorting of smoke boxes. The system hardware consisted of the PLC, bar-code scanners, photoelectric switches, network switch, cylinders, encoder, touch screen and other components. The barcode values read by bar-code scanners were passed through the network to the PLC, and the PLC received the barcodes and compared them to the stored barcodes to determine the smoke box types. Specific sorting and positioning were realized by the synchronization signal generated by the code disc. The sorting error rate was reduced by the pulse interval algorithm. This system was used in the cigarette factory. The correct rate of sorting was increased from 92% to 100%. The system was reliable and it reduced the working intensity of the sorting staff. The production efficiency and the system reliability were improved.