Abstract: With the development of infrared monitoring and early warning system, more and more attention has been paid to the research of infrared small target detection technology. How to continuously and effectively detect the target position in a complex background has always been a major challenge for researchers. Based on the study of the characteristics of infrared point moving targets, this paper proposes a small target detection algorithm for multi-scale local gradient strength measurement. Firstly, a multi-scale image pyramid is constructed, and a fast and coarse small target detection method is proposed at multiple scales. Then, the difference between the target itself and the surrounding background is used to measure the intensity of grayscale changes in various directions in the local window. Then the most appropriate response based on these measurements is obtained. The experimental results show that the proposed method has better robustness under the background of complex and variable, and it has more effective detection performance under lower signal-to-noise ratio.