According to different imaging system,moving point target detection in image sequences can be divided into two categories：moving point target detection in infrared image sequences and moving point target detection in visible image sequences. Most of existing arithmetics are aimed at infrared image sequences,so the main purpose of this article is to look for a new detection method which can be used in the two kinds of image sequences. A new arithmetic of moving point target detection for cloudy sky background is proposed.In the stage of background suppressing, a method that combines high-pass filter with mathematic morphology filter is applied. Based on the idea of TBD, three frames are conjointed to accomplish target segmentation. Track energy cumulation is used to detect the targets.Theoretic analysis and simulation results prove that this arithmetic is simple and easy to be realized, it can be used in infrared image and visible image ,furthermore it has no restriction on target＇s velocity and direction.