Based on structured overlapping grids, Navier-Stokes equation teams with ke turbulent model solved with finite volume method were applied to numerically simulate flow field past external store on different suspension (chordwise, spanwise, vertical). Through analyzing the results, the conclusion could be reached: different suspension has different aerodynamic characteristic, for example, along the chaordwise direction with the same attack angle, the side forces appeare nearly the same, while the normal forces are obviously different; Along the spanwise direction, side forces are so different and more outer along spanwise, more larger of the forces; along the vertical direction, the interference between the wing and store is weak, and thus all the aerodynamic parameters become smaller.