Abstract: In order to further stabilize filter rod forming, a geometry model of fluid domain of filter rod tow transport jet was developed with Solidworks. The air flow field inside the jet was simulated by Comsol Multiphysics to obtain the air flow field distribution inside the jet. The developed fiber moving model was solved by Matlab based on the data of air flow field to grasp the movement of fiber inside the jet. The results showed that the clearance between the sleeves influenced the air flow field distribution and fiber's movement inside the jet greatly, the deviation of air flow distribution and fiber alignment inside the jet increased with the increase of the clearance. Therefore, reducing the clearance of the jet could alleviate the fluctuation of the pressure drop of filter rod.