To solve the problems of low model simulation accuracy and slow simulation algorithm running speed that is not suitable for actual production needs caused by neglecting particle motion collision in the existing air separator of tobacco cutting workshop during the tobacco stem shreds air separation process, this paper proposes an equipment optimization research strategy based on particle suspension characteristics for the Tobacco Stem Shreds Air separator. Firstly, using the principles of suspension separation and inertial separation, a two-stage separation device for tobacco stem shreds is designed, and a two-stage separation chamber model is established. Computational fluid dynamics (CFD) numerical simulation is used to study the separation chamber of the tobacco stem shreds two-stage separation device. Secondly, the Discrete Element Simulation Platform is introduced to improve and enhance the CFD strategy, and it is used for simulation analysis of the Tobacco Stem Shreds Air separator process to solve the problem of ignoring collisions during particle motion solely using the CFD strategy. Finally, a parallel computing strategy is introduced to construct a parallel discrete unit individual (DUI) based CFD strategy (DUI-CFD), which solves the problem of low computational efficiency in single-threaded DUI-CFD coupling simulation technology. The proposed method has been shown to accurately simulate the separation process of tobacco stem shreds in an air separator and achieve higher simulation calculation speeds, as demonstrated by the experimental results.