Abstract: Based on the large eddy simulation, combined with WENO scheme, the adaptive mesh refinement (AMR) technique and immersed boundary method (IBM), the supersonic flow (Ma=2.5) past a micro-ramp has been simulated. Our numerical results reveal that the wall-mounted micro-ramp can modify the flow structure of a boundary layer obviously. The detail flow structures and the vortex evolution around the separation region and the wake have also been visualized clearly. Meanwhile, it also indicates that the streamwise vortices and the vortex rings downstream the micro-ramp have the same important effects in controlling of the boundary layer separation, and that the interactions among themselves have been discussed. Our calculated results are in a good agreement with corresponding experimental data, provide an important detail for flow structures, and reveal the mechanism of boundary layer control, which can provide an important guidance for the related research.