Abstract: Steady simulation model of aircraft integrated thermal management system was established and simulation blocks were constructed on the platform of MATLAB software. Simulation was conducted for the system for different Mach numbers and different altitudes. The outlet temperature and flow flux of key components in the system were then obtained. Influences of Mach number and altitudes on temperature of each state point were analyzed. The results indicate that in the fuel subsystem, except one state point, temperature of other state point increases with the increasing of Mach number at the same altitude in different subsonic Mach number; In the subsystem of air cycle, temperature in all state points decreases and then increases with the increasing of Mach number. The results also indicate that in the fuel subsystem, except one state point, temperature of other state points decreases with the increasing altitude in the same Mach number; In the subsystem of air cycle, temperature in all state points decreases with the increasing altitude.