Abstract: An infrared radiation characteristic test is the only way to obtain the real radiation characteristics of an aero-engine. To study the influence of atmospheric parameter variations on infrared radiation characteristics in ground tests, the variation range of atmospheric parameters for stable engine radiation characteristics is proposed. In this study, the temperature, H₂O gas concentration, and pressure are considered as typical atmospheric conditions, and the engine steady-state performance calculation method is used to establish the component-level engine model. The simulation method of combining the mature commercial CFD flow field calculation software and self-developed numerical calculation software for infrared radiation characteristics is conducted in the 3-5 μm medium wave band. Effects of different atmospheric parameters on aero-engine infrared radiation characteristics. The results show that when the atmospheric temperature is in the range 253.15-273.15 K, the concentration of H₂O gas is in the range 0.001-0.004, and the pressure is in the range of 0.95-1 times the standard atmospheric pressure. The infrared radiation intensity of aero-engine is positively correlated with the increase of each atmospheric parameter. Therefore, using smaller atmospheric parameters in this range has the least interference in the measurement of the aero-engine infrared radiation characteristics.