Abstract: Large eddy simulations based on the CFD software OpenFOAM have been used to study the effect of Reynolds number and turbulence intensity on the flow and mixing characteristics of an argon thermal plasma jet. Detailed analysis was carried out with respect to four aspects: the average flow field, the instantaneous flow field, turbulence statistical characteristics and the self-similarity. It was shown that for the argon thermal plasma jet with low Reynolds number, increasing the turbulence intensity will increase the turbulent transport mechanism in the mixing layer rather than in the jet axis, leading to the faster development of turbulence. The effect of the turbulent transport mechanism increases with increasing Reynolds number. However, the characteristics of flow and mixing are not affected by turbulence intensity for high Reynolds number situations. It was also found that the mean axial velocity and mean temperature in the axis of the turbulent thermal plasma jet satisfy the self-similarity aspects downstream. In addition, decay constant K is 1.25, which is much smaller than that (5.7–6.1) of the turbulent cold gas jet and has nothing to do with the Reynolds number or turbulence intensity in the jet inlet.