Aiming for remote wide-area detection of weak and small aerial target under space-based complex observation conditions, the radiation interaction mechanism of complex background environment, such as solar illumination, clouds and earth surface, and aerial target was analyzed based on the full link of optical detection, and then the main environmental factors that affect the target radiation characteristics were proposed. After that, combined with the detectability characterization, the influence rules of environmental factors, such as different illuminations and various background types, on the target detection performance under different detection spectrum were studied. Finally, by taking a typical target as an example, the influence order of different environmental factors was ranked combined with the existing target characteristics cognition and theoretical modeling, and the detection spectral optimal selection suggestions were given according to the change characteristics of target signal-to-clutter ratio with spectral bands, which provide theoretical basis and scientific guidance for the design of stealth/anti-stealth aircraft, space-based detection system and information processing optimization algorithm.