Aiming at the different characteristics of different components of infrared image under cloudy sky background, on the basis of background prediction algorithm of the infrared point target detection, this paper analyzed and compared the performances which three background prediction masks behaved in the detection process of background prediction, background suppression and threshold segmentation. The experiment results indicated that the three background prediction masks had different effects on different components of the cloudy sky background. Before choosing the better background prediction masks for application, proportion and diversity between different components of the cloudy sky background of infrared image should be distinguished.