Abstract: To study the effect of transition flow and turbulent flow on the shock wave boundary layer interactions and base flow structure, the models of 2 dimensional and 3 dimensional double ramp inlets and one big blunt lander model were chosen. The γ-Re_θ correlation-based intermittency model was used in the study. Research results show that, for a 2 dimensional inlet model, with the leading edge bluntness increasing the position of shock wave boundary layer interactions moves upstream and the separation flow region changes larger. Comparing the status of laminar flow the position of shock wave boundary layer interactions moves downstream and the intensity of the separation flow is weakened under the transition flow condition. For the 3 dimensional inlet model, near the corner the separation flow presents the characteristic of 3 dimensional flow structure and the 3 dimensional transition flow structure also occurs. Comparing the results under the quiet and the noisy tunnel status the transition flow occurs in the latter, and makes the strong effect on the wall heat flux but no effect on the shock wave system. For the blunt lander model the calculation results show that the transition flow occurs in the base flow region. It causes the base flow changes from the laminar unstable nonstationary flow to the turbulent stable stationary flow. This is beneficial to the design of attitude control.