Abstract: A numerical investigation was conducted about the shock structure at the entrance of the inlets and the effects of entrance flows on aft duct flowfields for a Caret inlet,and also the effect of the fillet circle and shielding region of oblique shocks.N S equations with the standard k-εturbulence model and near wall functions were employed to predict the flowfields.The results showed that asymmetry of oblique shock doesn't affect evidently duct flow due to the existence of strong normal shock.But the flow in the intersection of dual ramp affects evidently the flowfield of aft duct.