Detection and extraction of the dim moving small objects in the infrared image sequences is an interesting research area. A system for detection of the dim moving small targets in the IR image sequences is presented, and a new algorithm having high performance for extracting moving small targets in infrared image sequences containing cloud clutter is proposed in the paper. This method can get the better detection precision than some other methods, and two independent units can realize the calculative process. The novelty of the algorithm is that it uses adaptive thresholding technique of the moving small targets in both the spatial domain and temporal domain. The results of experiment show that the algorithm we presented has high ratio of detection precision.