Abstract: In order to improve the performance of axisymmetric mixed-compression supersonic inlet with fix-geometry,the performance of a supersonic inlet with cavities at the cone surface or the cone's corners was investigated by the numerical simulation.The effects of the cavities position on the cone on the performance of the inlet and the boundary-layer were presented.On the one hand,the shocks on the cones and the inlet's entrance Mach number were changed.On the other hand,the thickness of the boundary layer behind the cavities was increased and the velocity distribution in the boundary layer was also changed.When the cavities were at the cone's surface,the boundary layer thickness behind the cavities at the second and the third cone surface increased 33.3% and 52.4%,respectively.When the cavities were at the cone's corners,the boundary layer thickness behind the cavities increased 16.7% and 9.1%,respectively.The inlet's pressure recovery and the pressing ratio with cavities were higher than no cavities at high Mach number(3.7 to 4.5).Under design condition,the inlet's pressure recovery at the cavities of the cone's corners increased about 1.8%,and the pressure recovery at the cavities at the cone surface increased about 4.3% than no cavity.Besides,the mass capture ratio and starting Mach number were not influenced by the cavity at the cone's corners.