Abstract: A cold jet exhaust or a somewhat equivalent gas jet exhaust or a non-reacting gas mixture exhaust is usually adopted to study the jet interaction effects in experimental or computational work, but problems may arise in the design work of an advanced future vehicle using a divert thruster. Firstly the experimental and computational results in the available literatures about the influence of different gas models on the force and moment are reviewed. Then as a supplement study result, the forces and moments acting on the body, and the peak aerodynamic heating exerting on the lateral jet interaction areas by the cold jet exhaust plume, the non-reacting mixture jet exhaust plume and the reacting mixture exhaust plume models are presented for a typical cone-cylinder-flare body with a practical-use high momentum ratio divert jet. The calculated results show that when the lateral jet is turned off the chemical reactions have very limited influence on the forces and moments, but when the lateral jet is turned on the three different gas models give 4%~15% difference for normal forces and about 20% difference for interaction pitching moments. As the cold jet model can not be used to predict the aerodynamic heating property the chemical reaction effects on the peak aerodynamic heating exerting on the lateral jet interaction areas are studied by comparison between the non-reacting gas mixture model and the reacting gas mixture model, and 13% increase is found when considering the chemical effects. The lateral interaction mechanical property and peak heating results for the cone-cylinder-flare body with practical-use high-momentum ratio divert jet put forward a demand for experimental verification reproducing high temperature exhaust plume reaction effects.