Abstract: This article introduces the mechanism of Narcissus effect in the infrared scanning system.Two serious Narcissus cases which are familiar in the infrared scanning system are examined by analyzing the paraxial optical path in the practical optical system.Aiming at these two cases,two methods are described to restrain the narcissus effects in the optics design. Finally,this article analyzes the impact of coating on the Narcissus effect based on a practical example.And then the calculation and data analysis results are presented according to the coating films with different reflectivity values.