Abstract: In the study of the advanced aerodynamic fighter configuration,the location of twin vertical tails is always an important problem. In this paper, a fighter model of canard configuration was studied. The study includes three parts: measurement of aerodynamic force, flow visualization and PIV experiment. It is found that when the twin vertical tails are located on the back-inner of fighter's body, the maximum lift coefficient is max. The process of vortex breakdown and flow character are very similar with the state of no vertical tails. This indicates that the main effect of twin vertical tails on wing vortexes promote the vortex breakdown, so the aerodynamic characteristics of fighter will be deteriorated.