Abstract: Abstract In this paper, numerical simulation has been used to research the flow characteristics and mechanism of transport aircraft aft-body, vortex generators were used to control separated flows of aft-body, and it got an analysis of drag reduction mechanism by controlled, and also discussed the effect of different parameters on drag reduction. Calculation results show that: the drag of transport airplane aftbody is mainly caused by the flow separation of aft-body; vortex generators were fixed on the bottom of aft-body, and reached a certain drag reduction in the negative angle of attack. Size, circumferential distance and the forward or after location on the body of vortex generator have a certain influence with the drag reduction results.