A flow visualization and pressure distribution measurement test have been performed to understand the flow characteristics of swept wing/body junctions better. Different small strakes have been used to ameliorate the characteristics. The results show that with the increase of the angle of attack and the Reynolds numbers, two or three horseshoe vortex systems may appear. The steady vortex system may be changed into the unsteady vortex system and transferred into turbulent flow. With the increase of the swept angle of the wing, intensity and the size of the horseshoe vortex are decreased. It has been shown that the pressure gradient upstream of the wing/body junctions is the cause of the boundary layer separation. When the swept angle is decreased, the pressure gradient can be also reduced. The small strake is able to decrease the pressure gradient and makes the vortex weaken or even disappear upstream of the interference zone.