Aiming at the imaging characteristics of the water bodies of synthetic aperture radar images, and to solve the problem of blurred edges, a water body target extraction method based on region growing and Markov Random Field (MRF) was proposed.Firstly, considering that the water surface in SAR image is a uniform and low-intensity region, we used watershed method for segmentation, and defined the blocks with large area as the seeded region of water body.Then, region growing was carried out using the statistical characteristics of the region, and the initial water body targets were obtained.Finally, the precise water bodies were extracted from the initially segmented images by the MRF model that combines the local uniformity characteristics of observed image.The experimental results show that the proposed method can accurately extract the water body targets in SAR images and accurately locate the target edges.