Aiming at the problem of detecting and identifyingto ground target for 3~5 μm airborne medium wave infrared system in complex meteorological conditions, based on the theoretical research, by the use of PcModWin atmospheric simulation software, the simulating experiments are carried out for the meteorological conditions of clearness atmosphere, fog, cloud and rainy. The distribution curves of this wave band infrared radiation transmittance and the variation law of peak parameters in thedifferent distance range under different conditions are analyzed. Combined with the theory of atmospheric molecules, the detection angle, atmospheric visibility, fog type, cloud type, rainfall (snowfall) intensity, etc., are proved the important factors that affect the effect of detecting and identifying toground target for this wave band airborne infrared system. The strategy methods is put forward which should be taken in engineering application. The researched conclusion not only has an important guiding role in following engineering tests and application practices, but also has an important signification in rising the application effect to thiswave band airborne infrared system.