An evaluation and analysis method for space-based infrared system (SBIRS-H) performance is proposed based on the simulated radiation scene data.The relationship between overall specifications of detection system and detection performance is built.The scene clutter is quantitatively described by introducing the clutter-equivalent-target.The signal-to-clutter ratio is used to characterize the integrate detection performance，and this method can reflect change rule of detection performance at different parameters.The proposed method could be applied for the analysis，design and evaluation of the infrared detection system.