Abstract: A new algorithm of real-time detection for infrared motion small targets in rotational and complex background is proposed for solving the problems of high error rate of detection and poor real-time performance. The algorithm, at the first, processes the original infrared image with median filter, calculates the optical flows field, extracts the image's feature points, estimates the background optical flows field, and then extracts the assemblage of the target feature points by setting the threshold. Finally, according to the optical flow vector angle of feature points, target gray interval and the area of feature points of edge detection, the background features points are removed from the assemblage, and thus the infrared motion small targets in rotational and complex background are detected accurately and timely. The experimental results show that the rate of detection of infrared motion small targets reaches 93.8%, the rate of average false alarm is 0.126 times per frame, the average time of target detection per frame is 15.53 milliseconds, and the maximum processing time for each frame is 20.45 milliseconds. It is concluded that the proposed algorithm meets the requirements of real-time moving target detection.