Small target under the low contrast is often disturbed by a large number of background clutter and noise,so it is difficult to detect the small target. An infrared small target detection algorithm based on the human visual attention and adaptive dual structure elements morphology filter was presented．Based on human vision mechanism,the ROIs of the image are extracted to determine the candidate targets,and then the sizes of the candidate targets was obtained by extracting its contours,which adaptively constructed the structural elements of morphology filter. In ROIs,clutter and noise signal were suppressed by using the adaptive dual structure elements morphology filter,and then clutter and noise signal were further suppressed by using median filter. Experimental results show that the algorithm can suppress noise signal effectively,improve SCR of the targets and detect the infrared dim small target accurately,and it has good robustness and real-time performance.