Abstract: With flat after-body, large cargo aircraft have simpler structures, less weight, and the port machine has high dependability. However, the flat after-body induces strong transverse flow and flow with high adverse gradient when the aircraft cruises, so the boundary layer on the after-body is easier to separate. Separated flow increases pressure drag, and the separated vortex worsen the pressure distributions on the both side of vertical tail when the aircraft yaws. So the yawing stability is reduced. The chine is a special aerodynamic device which is used on flat after-body. It can restrain the birth and development of vortex flow. When the aircraft yaws, the chine can also enhance yawing stability by improving pressure distributions on the surfaces of vertical tail and after-body. Because of the functions of drag reduction and stability enhancement, the chine makes the transport aircraft with flat after-body having both high load efficiency and satisfied aerodynamic performance.