Vortex-wing interactions affect the efficiency of formation flights and the safety of paired approaches. A numerical simulation study is developed to investigate four situations, including a follower wing without stable incident vortex, and stable incident vortex on a follower wing at three typical spanwise locations. The vortex-wing interactions between stable incident vortex and a follower wing is studied. Three-dimension vorticity based on Q-criterion, vorticities at different streamwise locations, surface pressure coefficient in suction side, aerodynamic coefficients and rolling-moment coefficient are analyzed by comparison. The results show that, when the stable incident vortex is outside or inside the tip of the follower wing, the tip of the follower wing is at the down wash or up wash region. Wing-tip vortex is restrained in both locations. Lift coefficient, lift-to-drag ratio and rolling-moment coefficient increase as the stable incident vortex getting close to the tip of the follower wing and reach maximum, when incident vortex is coincide with the tip of the follower wing. Such results could provide references for formation flights and paired approaches.