Abstract: To discuss the influence of air Suction Slots on the fiber condensing effect , the numerical simulations of the flow distribution in complete condensing spinning system is given by using Fluent software. Corresponding simulation results of airflow distributions in condensing area with three different air Suction Slots are obtained. The results showed that the shape of the suction slot have a great impact on the airflow distribution in condensing zone. The long and short oblique grooves have better condensing effect in the entire condensing area, but they may have negative effect on spun yarn evenness; the Z-axis velocity distribution of long oblique groove can weaken the agglomeration effect. The straight groove may spread the sliver again in the median space. Finally, the theatrical results obtained are illustrated by experiments.