In order to study the possibility of aerodynamic optimization of the base cavity for slender body, the influence of base cavity with non-cylindrical shape, which is different from the traditional column one, is investegated by numerical method in the paper. The supersonic flow field of same slender body with two sorts of unconventional base cavity, which is half truncated-cone and half column, is simulated by axisymmetric Navier-Stokes equations. Distribution of Mach Number (Ma), streamline, temperature and pressure of the flow field; the aerodynamic drag of the slender body were calculated. Compared with the traditional cylindrical base cavity structure, results show that, the appropriate non-cylindrical base cavity is helpful to decrease the aerodynamic drag of slender body. In the paper’s simulation, the slender body with the base cavity of half truncated-cone (negative inclination) and half column shape has the smallest aerodynamic drag. The cylindrical base cavity structure, which is widely used to reduce the aerodynamic drag, there are spaces to further optimize still.