Abstract: Narcissus refers to the case that the cooled detector can see its own reflecting image, which may affect the image quality of infrared system seriously. In the process of optical system design, the controlling of Narcissus intensity is often contradicting with the improving of image quality and satisfying of boundary requirements. Simulation analysis and evaluation method of Narcissus intensity were presented in detail. A quantitative model was proposed for calculating the ratio of Narcissus radiation signal with system noise. By building a proper platform, the simulation analysis and experimental test about the Narcissus intensity of two infrared systems were carried out. The results show that the Narcissus intensity of the experimental test is consistent with the simulation result. Therefore, Narcissus intensity can be effectively evaluated by simulation analysis and quantitative calculation in optical design to ensure the quality of optical system.