Abstract: An analysis of the impact of internal performance on the counterflow thrust vectoring nozzle under different flight conditions was presented by numerical simulation. The results show in static conditions counterflow phenomena occurs on two nozzles of different slot hights when the secondary pressure is at 60 795-87 139.5 Pa and 50 662.5-91 192.5 Pa without jet attachment. And with the secondary pressure increasing ,the pitch-thrust-vector angles decrease and thrust ratios increase. When the Ma number is 0.6 and 1.2, jet attachment occurs on the nozzle with smaller slot hight and can not apply to actual fluidic control. But to the nozzle with larger slot hight, when the Ma number is 0.6,counterflow phenomena occurs at secondary pressure 40 530-87 139.5 Pa without jet attachment. When the Ma number is 1.2,there is no counterflow phenomena at considered secondary pressure.