Abstract: In order to study the difference of aerothermal environment between the Earth's atmosphere and Titan's atmosphere, the numerical method was adopted to simulate the aerothermal environment in the flow field in front of the Titan detector. It is found that, compared with the Earth's atmosphere conditions, the heat flux on the detector surface is higher under the Titan's atmosphere conditions. Its peak value can reach more than 1 time of the Earth's atmosphere conditions. The heat flux on the detector surface first increases with the decrease of height and then decreases when the velocity is less than a certain degree. The dissociation reaction of CH₄ occurs to a large degree within the shock layer, and the strong radioactive substance CN generated by the replacement reaction forms a small shock thin layer before the detached shock wave. With the increase of attack angle, the heat flux on the lower surface increases while that on the upper surface decreases. Therefore, when the detector enters the atmosphere at a certain angle of attack, the thermal protection of the lower surface is very important.