In the simulation of high enthalpy flow in an arc-heated wind tunnel, based on the characteristics of complex flow field at high temperature, the flow parameters in the inner and outlet of the nozzle, and the heat flux distribution on the wall of the typical model were compared under various numerical calculation conditions, such as different thermochemical models, wall catalytic conditions, flow field integrated and separated calculation. The numerical calculation results show that the surface heat flux of the single temperature heat equilibrium model is higher than that of the double temperature heat non-equilibrium model 6.99%. When the test model is close to the nozzle outlet, the separated calculation of flow field can improve the calculation efficiency. However, the integrated calculation must be adopted to ensure the calculation accuracy when the test model is far away from the nozzle outlet. At the same time, the wall catalytic effect has been studied at the high enthalpy flow in arc-heated wind tunnel. The surface elements of 3 types of heat flux sensors were analyzed by X-ray scanning electron microscopy, and the influence of surface catalytic properties of heat flux sensors on aerodynamic heat measurement was studied. The results indicate that the wall catalytic effect can significantly increase the surface heat flux of the test model. Combining the numerical calculation results with the test measurement results of slug calorimeter, it shows that when the slug calorimeter with oxygen free copper matrix is used for arc-heated wind tunnel heat flux measurement, its surface will be oxidized to CuO. The numerical simulation results of with limited catalytic wall condition γ=0.022 are closer to the experimental results. It is also consistent with the catalytic recombination coefficient of CuO in the literature.