Effects of secondary sonic jet injection in divergent part of supersonic nozzle on flow field structure and thrust vector control performance has been numerically analyzed. Three dimensional multi-blocks extended numerical code has been used to model the complexity of turbulence flow by k-ω SST model. Structured computational domain has been applied and initial results of simulation validated with previous experimental results. The obtained numerical results are compared with the experimental ones, and the outcome shows acceptable agreement between the two. Different injection power generates by varying the injection surface and pressure ratio with respect to throat pressure. Injection power increment make changes in performance and also sometimes it lowers the performance. In the current research aside from complete complex flow features description, allowable power range to increase system performance has been presented. In this range, increasing the injection mass flow rate, decreases the amplification factor, but increases the deflection angle and axial thrust augmentation as most important performance parameters. Out of estimated range for allowable mass power injection, performance parameters different behavior differently that shows a drastic drop in performance.