In study of the influence of the infrared detector IWR readout mode in the search system on the imaging of adjacent frames,it is found that,in the IWR readout mode,when the thermal imager images the strong radiation target,the residual image phenomenon,the white and black shadows will appear.To solve this problem,this paper has carried out a lot of theoretical and experimental analysis to explain the cause of the afterimage phenomenon.By modeling the afterimage phenomenon,the parasitic capacitance formula is deduced,and the rationality of the formula is verified.It is analyzed through experiments that the residual image intensity is mainly related to the temperature difference between the target and the background.The larger the temperature difference,the more obvious the residual image phenomenon.Finally,this paper analyzed the influence of the afterimage phenomenon on the search system,and proposed a way to reduce the intensity of the afterimage.