Abstract: Aimed at improving stable rejection effect and rejection rate caused by wet tobacco caking in the two-stage pneumatic separation system, a three-stage pneumatic separation system was designed and its performance was evaluated. The optimal combination of key technological parameters of all the separation stages was determined based on the differences in raw materials and processing tasks at each separation stage. The results showed that the optimal combination of parameters was as follows: the primary stage valve opening at 56% (the primary valve opening should be reduced by 3 percentage points when the moisture content in the cut strips was below 12%), the second stage fan motor frequency at 31 Hz, and the third stage valve opening at 61%. After the optimization, the amount of rejected wet tobacco caking increased by 1 074.30%, the amount of rejected stems increased by 10.70%, and the cut strip content in the rejected stems decreased by 37.84%. Both the proportions of integral and short tobacco strands and the fluctuation in moisture content of the cut strips met the technological standards, and the main indices of the finished cut strips and resulting cigarettes did not change significantly.