Abstract: For separating tobacco stem from lamina effectively, a new optical stem sorter was added to the existing tobacco threshing line, and experiments were conducted for validation. The results showed that:1) The efficiency of the optical stem sorter decreased with the increase of tobacco processing flow, the stem rejection rate of the device was above 90% and the false rejecting rate was below 10% when lamina flow rate was less than 1 400 kg/h. 2) Taking into account that the tobacco came out of the fifth and sixth pneumatic separators had the highest stem content in the current threshing line composed of 4 threshers and 12 pneumatic separators, an optical stem sorter was added between the fifth and sixth pneumatic separators and the second stage thresher. 3) Verification results indicated that by combining pneumatic separation with optical stem sorting, the overall stem content in lamina reduced from 2.06% to 1.33%, or reduced by more than 35%; the undesired stem content in lamina decreased from 0.46% to 0.14%. The application of optical stem sorter effectively promotes stem-lamina separation quality.