Abstract: By analyzing the problems existing in manual knife setting and replacement on the cutting drum in tobacco cutter, an automatic system was developed by using existing cutting drum power source and PLC. The speed of cutting drum could be randomly adjusted in the range of 0 rpm to maximum rate, the position of individual knife could be automatically set and locked by inputting the respective knife number into PLC via touch screen. The system is safe and labor saving, and it enhances the automation of the machine.