Abstract: Characteristics of hypersonic laminar separation induced by the control surface of a HTV-2 like configuration were investigated numerically. It is found that the patterns of the separations induced by the control surface have long flat shape and a pair of counter rotating vortices. These patterns are very different from those induced by a rectangle plane/3D wedge. A detailed analysis was carried out to explain this behavior. Studies were also conducted to examine the effects of the flap deflection on laminar separation. Interestingly, since the influence of the forebody shape of the HTV-2 like configuration, the flow gathers from both sides to the middle and pressure gradient boosts before the control surface. A separated flow is still induced because of the control surface, even at the angle of deflection as small as 5°. This phenomenon is in a good agreement with the experimental result, and is different from the generally understanding about initial separation angle of compression corner.