The axial inlet vane-type multi-tube separator’s structure and separation efficiency were analyzed based on the Navier-Stokes and continuity equations using the Reynolds stress model and the finite volume method. The velocity and pressure field of a single cyclone tube were simulated, and a discrete phase model was applied to study the separation efficiency by analyzing the motion pattern and the trajectories of the particles with different sizes in the separator. The results showed that the vanes’ channel blockup could cause an eccentric annular air separation space and that its affected width and depth both increase with increasing jammed vanes. Jammed vanes intensify the local pressure, velocity and pressure drop. The comprehensive influence of eccentric airflow and local speed should improve the separation efficiency as the number of jammed vanes increases. The separation efficiency should not decrease, but the pressure drop and energy consumption will both increase, thereby substantially reducing the processing volume if the compressor continues to provide invariable output power. However, this situation would not result in poor-quality natural gas in the short term. If the separator can meet the requirements of natural gas processing under normal circumstances, then the blockup should be cleared over time once it is able to maintain the rated processing capacity and reduce its energy consumption, which could stabilize the load of the gas-transmission devices.