Abstract: The numerical simulation to study the internal flow characteristic of an axisym-metric vectoring nozzle under outer flow has been conducted with collocated finite volume scheme. The results of simulation have been compared with that of experiment. The effect of different NPR and outer flow on internal performance of axisymmetric vectoring nozzle with deflective angle of 20?has been analyzed. The investigation shows that the separation shock wave gives an important effect on internal performance of axisymmetric vectoring nozzle.