Negative pressure plays a very important role in compact spinning system. To know airflow field and its distribution is helpful to look into the condensing principle of fiber bundle. Therefore, computational fluid dynamics (CFD) software was used to simulate airflow field in this paper. Airflow velocity distributions both in different fiber layers and under different negative pressures were discussed. The results indicate that airflow velocity in upper layer of the fiber bundle is greater than that in lower layer.Airflow velocities in both X and Y axis directions have a positive correlation with negative pressure. It can provide a theoretical base to make high quality compact yarns in productive practice.