Abstract: Three-dimensional gas flow field in the new vortex quick separation system with an inner component of FCC disengager was simulated based on the Reynolds stress model（RSM）provided by CFX. Predictions with the Reynolds stress model（RSM） were in reasonable agreement with experimental results measured by intelligent five-hole probe.The trajectory of the particles was computed by introducing the discrete random walk tracking model, through which the grading efficiency and general efficiency of the vortex quick separator could be simulated.Numerical calculation showed that the inner component could eliminate the short-circuit flow near the vortex head and help to improve the separation efficiency of the vortex quick separator.Comparison of the particle trajectory and separation efficiency between the generally used VQS system and this new system with an inner component showed the performance of the latter better than the former.