Hydrothermal jet is an alternative drilling method for the exploitation of oil and geothermal energy in deep hard formations. For the application of this novel technology, the successful generation of hydrothermal jet is very important. This paper focuses on investigating applications of different reaction, turbulence and radiation models to the supercritical water oxidation process in downhole reaction chamber of hydrothermal jet drilling. The objective is to identify the pros and cons of each model and determine a set of models that are the most appropriate for the reaction. Simulation models are tested and optimized through two different operating conditions. Simulation results are compared with experimental data. Results show that the entire space of the reaction chamber is in a high temperature state using the laminar finite rate model. The finite rate model is suitable for the simulation compared with other reaction models discussed. The Magnussen constant A and B in the finite rate model can be modified to be 7 and 0.5 to further reduce the error. In addition, the high temperature areas in k-omega model and SAS model are more concentrated, while they are more uniform in RNG k-epsilon model and standard k-epsilon model. The RNG k-epsilon model and DO or DTRM are the most appropriate turbulence and radiation models through comparison. Results in this paper can provide implications for the reaction simulation of hydrothermal jet drilling. (C) 2018 Elsevier Ltd. All rights reserved.