To solve the problems of false segmentation and false tracking caused by the interference of background when moving infrared targets are being detected against harbor background, a moving infrared target detection method based on harbor background suppression and optical flow detection is proposed. First, OTSU segmentation is carried out for a wavelet segmented image, so as to obtain the sky-sea line. Secondly, a multi-level filter is used to locate the background suppression points in sequential images, so as to suppress the harbor background according to these background suppression points. Finally, an optical flow prediction technology is used to realize the detection of the moving infrared target. The feasibility and effectiveness of the method are verified in the experiment of background suppression and moving infrared target detection against the actual harbor background.