The s ea-land segmentation of SAR image is important in the marine applicatio n s, such as target detection, coastline extraction, etc. According to the charact eristics of SAR image, this paper puts forward a threshold segmentation algorith m combining rough threshold with accurate threshold, and provides a complete set of sea land segmentation scheme. Firstly, Otsu method is used to calculate a ro u gh threshold, and then the rough sea area can be obtained. Secondly, according to the feature that statistical characteristic of sea area similar to Gauss dist ribution, an accurate threshold can be calculated on the basis of rough threshol d segmentation, then the accurate sea land segmentation image can be obtained. F inally, [JP2]the segmentation result can be improved by the operation of removing spe ckle. The experiment results show that the proposed algorithm has high processin g precision and quick processing speed.[JP]