The pre-cooler is an important part of the temperature adjustment of the pneumatic system of the civil aircraft. Over temperature of the system will lead to automatic shutdown of the system, which will affect the demand of downstream wing anti-icing system and air conditioning system, and have a significant impact on the safety of aircraft. Therefore, the research on the pre-cooler design point is of great significance to the design of the pneumatic system. Firstly, this article analyzes the influence relationship of the heat transfer performance of the pre-cooler, and then analyzes the factors affecting the performance of the pre-cooler, including environmental conditions information, aircraft state information and air source configuration. Then, according to the empirical formula, the heat transfer power factor of precooler under different conditions of a certain model was calculated. The calculation results show that low altitude, low Mach number, and low weight are the pre-cooler design points under the dual-engine single-bleed configuration, in extremely hot day, under cruise or holding operating conditions. In addition, this paper verifies the design point of the precooler by calculating the hot side outlet temperature of pre-cooler under harsh working conditions. The calculation results show that the hot edge outlet temperature of the pre-cooler meets the expected temperature of the precooler, indicating that the selection of the design points of the pre-cooler meets the design requirements.