Abstract: The vortex system of a large aircraft afterbody includes a counter-rotating vortex pair (APV) generated by the afterbody separated flow and horizontal tail tip vortices (HTV). The characteristics of the vortices of a simplified afterbody with and without horizontal tails were measured in the wind tunnel using PIV. APV shifts upwards when moving downwards. A four-vortex system is observed for the afterbodies with horizontal tails. APV is significantly affected by HTV:APV shifts upwards faster and moves outwards in spanwise direction; the existence of HTV strongly reduces the vorticity strength of APV. The restraint effect becomes stronger as the span of horizontal tail decreases. Inflow speed has little to do with non-dimensional parameters of the vortices under low speed conditions.