It is an important task to detect and track the lowly observable and small targets in a sequence of infrared images against cloudy background. A simple and practical scheme about dim small target detection in cloudy background is given. In this scheme, the first step is to suppress the background clutter to obtain the higher SNR of the images. The second step is to segment the image using a threshold to get a binary image. According to the movement continuity of targets in temporal and spatial domain, these targets are identified by a pipeline method. The experimental results prove that the algorithm is very effective.