This paper propose a new coastline extraction method for polarimetric SAR images. Through detailed analysis of the polarimetric SAR (PolSAR) data，this paper selects the polarimetric entropy as the basis of the edge detection and coastline extraction since it is sensitive to the polarizationdependent variation of texture. Firstly, the polarimetric entropy image is used to generate the edge maps including an edge intensity image and an edge orientation image. Based on the edge maps, a new “coarsefine” method is proposed to extract the coastline. The latter is divided into three steps: first, a rough contour is extracted based on the edge orientation image; second, significant edge points, which are named control points, are extracted based on the edge intensity images, then correct the rough contour by using the control points and achieve the final coastline. The proposed method is used to extract the coastline on the Radarsat2 quadpol data and the results prove that the proposed method could better delineate the coastline than the comparative methods.