Abstract: In order to solve the problem of low contrast, fuzzy edges, and inhomogeneous target gray level in the ship infrared image segmentation, an interactive segmentation method based on graph cut and fuzzy connectedness is proposed. The interaction process uses a rectangular pen brush for selecting the seed points of target and background. The segmentation method is based on graph cut method, in which fuzzy connectedness is introduced to compute the likelihood energy of graph cut, and the automatic computation of its weights is also given, furthermore, a histogram decomposition method is proposed for estimating the number of components of a mixture and the parameters of that model. The simulation results show that the proposed method can segment ship infrared image target effectively under various complicated environments.