Within the complete temperature envelope of the aircraft, it is necessary to ensure the temperature safety of the hydraulic system and eliminate hidden dangers. This article establishes a thermal characteristic model of the aircraft hydraulic system in AMESim through simulation methods. The temperature of each critical point of the hydraulic system under special weather conditions was simulated and analyzed. Under the condition of high temperature weather, with the passage of time, the temperature of each key point of the hydraulic system will rise sharply, the highest temperature is the shell oil return temperature, which is 80.4 ℃, the temperature of the pump inlet is significantly lower than pump outlet and the shell oil return temperature, in the low temperature weather conditions, the temperature of the hydraulic system in the shell oil return has reached the maximum, about 30 ℃, the temperature of the pump inlet and the temperature of each user are successively lower than the shell oil return temperature, and this characteristic provides strong support for the temperature envelope design of the subsequent hydraulic system.