Abstract: Installation of swirl nozzle in ring spinning can reduce yarn hairiness. Using STAR-CCM+ software to numerically simulate the flow field inside the swirl nozzle, which can show the distribution of flow field of the nozzle yarn, and explain distribution of radial, tangential and axial velocity of the yarn path in nozzle. When the nozzle channel and the yarn path intersects in different directions and tangent points, combined with the effect of air flow on the fiber, we can realize the airflow distribution of yarn channel in swirl nozzle. Drawn from the simulation results: the tangency point of yarn path and airway of swirl nozzle along the negative X axis length is 14mm, and the direction intersects of the yarn path and the nozzle channel is upward. This swirl nozzle can reduce the majority of forward hairs.