For the space-based ultraviolet (UV) detection system, quantitatively estimating the clutter radiance from the fluctuations of earth-atmospheric background is beneficial to effectively select the detecting channels (including middle- wavelength and spectral- range) in different scenes, and can improve the comprehensively detecting performance for the space target. Based on the space signal transfer, the space clutter radiance models in different scenes are established in the UV window of 290~400 nm. By means of the models, the main influence factors for the space background clutter radiance are analyzed. In the level of the possible target radiation characteristics and earth-atmospheric background clutter radiance, the detecting performance of system influenced by the clutter is effectively estimated. The results show that the middle-wavelength and spectral-range of detecting system should be 300 nm and 297~306 nm for clear sky, but 299 nm and 296~303 nm respevtively for the field of cirrus clouds.