Abstract: In order to study the influence of feed position on the counter-current in gas centrifuge, direct simulation Monte-Carlo (DSMC) method was chosen to simulation the rarefied region of gas centrifuge. By setting Iguassu centrifuge model and variable hard sphere (VHS) model, the flow distributions of different feed positions were acquired. The analysis of the calculation results notes the following flow phenomena: In case of radial feed, the region near the feed outlet is largely influenced by the feed condition. The expansion of jet results in the hypothermic region. Near the boundary of effluent, due to the fast peripheral velocity, pressure gradient is large, which results in the slow radial velocity and the high temperature. The axial translation of the jet results in the axial translation of the flow distributions. With the increase of the radius of feed, the region of expansion near the feed reduces and the lowest temperature of the hypothermic region rises. Near the boundary of effluent, with the increase of the radius of feed, the temperature and the radial velocity fall.