Abstract: The three-dimension Navier-Stokes equations are solved to reveal the aerothermal behavior of the cavity-like structure of protuberance on the surface of flight vehicles. Based on the calculated supersonic flow field and the local heat flux, the aerothermodynamic mechanism of the cavity-like structure is discussed. It is indicated that the heat flux peak is at the front edge of the cavity. An optimized shape is designed for reducing the peak value of the heat flux injected to the front edge. It is shown that the heat-flux onto the front wall is reduced to only about 20 percent of the initial value with the original shape.