Abstract: To improve the efficiency and reduce the labor intensity of the case filling process before green leaf threshing, an automatic tobacco press mechanism for case filling system was designed. The designed press mechanism consists of two pressing plates, two driving devices and two position limiting units, and its automatic control program is integrated in the PLC controller in the case filling system. The swing angle of the pressing plates is controlled by the position limiting units. When the tobacco leaves filled in the case reaches the set value of 250 kg, the driving devices drive the pressing plates to press tobacco leaves to make room for receiving supplementary tobacco feeding of 10 kg. After 5 rounds of pressing and supplementary feeding, the tobacco leaves filled in the case reaches the upper limit, and the case filling process is completed. The designed press mechanism was tested on the case filling system in the green leaf threshing production line in Huili Redrying Factory. The results showed that the automatic press mechanism could dispense with manual leveling for tobacco leaves in the case, increase the average contents of tobacco leaves per case by 20% and increase the processing capacity by around 10% per shift. This technology provides support for improving efficiency and reducing labor intensity of tobacco processing.