Abstract: The flow field of a supersonic flow over a spherical body mixed with a counter-flow jet from the front stagnation point of the body is numerically studied by solving the asymmetric and three dimensional Navier-Stokes equations coupled with the standard k-ε turbulence model using the Van Leer’s flux vector splitting spatial discretion scheme. The effect of jet total pressure, jet exit size and the angle of attack on drag reduction of the body is systematically investigated. It is found that the flow field experiences a long penetration mode and a short penetration mode in sequence with the increasing of the jet total pressure when the jet exit size and angle of attack are fixed and there is a critical value of jet total pressure where an optimal drag reduction can be obtained. This critical value varies with the jet exit size ratio linearly. The results show that the maximum drag reduction can reach as high as 54.7% for the cases studied. With the increasing of the angle of attack, the asymmetry of flow field is enhanced and the drag reduction efficiency is reduced. The present results provide useful information on drag reduction technology of a supersonic blunt body in engineering applications.