In this paper,we extracted information dimension by using the theory of calculation of the box-dimension in the context of fractal theory and investigated the practical algorithm of this method.Based on this theory,two kinds of dimension were utilized to detect the coastline of X band and low resolution SAR image,which has been performed biparameter constant false alarm rate(B-CFAR) in advance.By conducting comparison of the testing results,a conclusion that our investigation of this method will have a posi...