The advantages of the Secondary Injection Thrust Vector Control (SITVC) system over conventional thrust vector systems include reduced weight and complexity due to the elimination of the mechanical actuators that are used in the vectoring and increased thrust by secondary injection. However, a strong bow shock at the ahead of the secondary jet is generated by the complex 3-dimensional flow field. The boundary layer/shock wave interaction results in boundary separation shock wave as well as strong recirculation flow including reattachment flow. As a result, local heat transfer is highly concentrated around the secondary injection hole. This could cause to thermal damage to the nozzle surface thus making difficult to maintain the system performance. Therefore, investigate the change of the flow field caused by the boundary layershock wave interference regarding secondary injection is requisite to thermal design. The momentum ratio and the injection angle of the secondary flow are as a parameter in this work. In this study we study the characteristics of the flow and heat transfer using numerical simulation, oil and lampblack method and Infrared thermography (IRT).