Abstract: In the highlands, thin air can reduce air conduction and convective heat transfer and increase radiative heat transfer. In this work, a numerical simulation was used to study the effect of heat radiation from the wall of a vehicle on the temperature field of the whole vehicle, especially under summer conditions in the highlands of China. Firstly, considering the influence of solar radiation and applying integral solution method, the conjugate heat transfer problem was calculated. And then, from both transient and steady-state perspectives. the effect was discussed for heat radiation of a vehicle to the temperature field of the whole vehicle, comparing with the situation of plain areas. The results show that for high altitude areas, the average temperature of the air in the car with wall radiation is 8.93K lower than that without wall radiation. In steady-state generally, the radiant heat transfer of the body accounts for 41.16% in the total send heat of the body. In the radiant heat transfer, the front windscreen, rear windscreen, engine hood, and seats account for 23.59%, 35.94%, 29.91% and 61.96%,respectively. Therefore, wall thermal radiation of a vehicle is an important form of heat transfer in high altitude regions.