To further reduce the tobacco filament content of the wind-separated stem mixtures, a signalized analysis model for the tobacco wind separator is proposed, and a loop separation design is proposed based on the results of the model. Frequency domain transformations and signal flow diagrams in signal systems are introduced into the analysis of wind separators to derive the signalized analysis model, which leads to the system function of the wind separator. According to this system function, the screening capacity of a general wind separator on tobacco is related to the wind field. However, the wind field of a general wind sorter is relatively simple, which makes it quite limited in separating the stems from the tobacco filament. The proposed loop separation design is capable of loosening the tobacco material several times in the wind field to reduce the probability of tobacco filament being mistakenly rejected due to agglomeration or tangled with stems. Comparing the results of the same brand of tobacco before and after applying the loop separation design on wind separators shows that the proposed loop separation design can significantly reduce the tobacco filament content of the wind-separated stem mixtures, which can bring great economic benefits for cigarette enterprises.