Based on the characteris tic analysis of infrared naval vessel target under the sea-sky background, a new adaptive infrared small target detection method is developed, which uses the LOG operator to detect the outline of the target and then decides its center point as the seed point in the region growing procedure. In the proposed approach, the parameters of the LOG operator are adaptively determined using the roughness estimation of the background.This procedure is a preprocessing method of the detection and recognition of the small target, and it can reduce the computation requirement, improve the detection speed, restrain the unnecessary seed points in region growing process, and increase the possibility of target detection.