Abstract: The air flow path resistances of the passive containment cooling system（PCS） in advanced nuclear power plants are analyzed with computational fluid dynamics（CFD） method which is verified and validated by tests. The results show that the resistance factors vary little as the flow velocity increases, while the main losses generated at air inlets, turning vane and inner annular. The flow resistances can be depressed by optimizing the turning vane geometry. Increasing the space of inner annular can reduce the resistance factor. Considering the heat transfer enhancement, the space ratio 1∶3 between inner annular and outer annular is appropriate.