To investigate the optimal configuration regarding the separation efficiency of the stile and the operational velocity of the cross-flow fan within the air branch cavity of the stile label conveying device in the winding unit, this paper developed a three-dimensional computational model of the z pipe utilizing Solid Works. Subsequently, the flow field and pressure field distributions were simulated employing Fluent analysis software. The pressure changes of the fluid in the z field screening system under different cross-flow fan speeds and the cut tobacco recovery rate and the cut tobacco stem removal rate under different pressure differences were analyzed. It was obtained that the airflow velocity in the z field screening system was proportional to the speed of the cross-flow fan v = 0.0049r−5.5, and the airflow produced a vortex in the z field separation chamber. With the increase of pressure difference, the recovery rate of tobacco is about 23.1%, which is proportional to the pressure difference, and the removal efficiency of tobacco is about 8.86%, which is inversely proportional to the pressure difference. When the rotation speed of the cross-flow fan is 1700r/min and the pressure difference is -350Pa, the separation efficiency of tobacco and tobacco stem in the z field air division chamber is the highest.