In order to solve the problem of huge demand and low production efficiency of ammunition, an automatic tightening device for ammunition is designed by taking the assembly of ammunition body and empennage as an example. The system includes the clamping structure of the empennage and the missile body, the tightening structure of the empennage, the control of the tightening torque, etc. The automatic tightening of the empennage of the missile body is realized through the PLC remote control. The results show that the device can make the automatic assembly of the projectile body and the empennage, ensure the assembly quality of the projectile body, reduce the error of manual operation, improve the production efficiency, and provide a new idea for the automatic assembly of ammunition, which is of great significance in military equipment.