Abstract: In the process of tobacco strips prepressing and packing, the temperature difference between tobacco strips and ambient environment might result in some wet strips. Therefore, an online vacuum cooling system was designed. The pressing head on the bale presser is replaced by a hollow pressing head with a vacuum suction mouth. The pressing head draws the humid and hot air out of the case through the suction mouth during downward pressing process, thereby reduces the temperature and prevents the formation of condensation inside the plastic bag. An opposite-blow cleaning device is used to prevent strips or tobacco dust from entering the vacuum pipe. The designed system was tested in Xianyang Tobacco Redrying Corporation Limited. The results showed that the proportion of wet strips in cases decreased by 1.995 percentage points, the average temperature inside cases reduced by 3.12 ℃. About 1.5 RMB yuan per case were saved in labor cost and about 240 thousand RMB yuan of steam cost for heating were saved per year. This technology provides supports for improving tobacco quality and reducing production costs in green leaf threshing.