Abstract: With traditional rectangular bi-window to detect non-ideal edge，iteasily detects an error about the edge point in the vicinity of the edge，and the test results will appear offset. Aiming at the limitation of traditional rectangular window that the function smoothing effect is poorer，designed a kind of Gauss-Gamma type double window function algorithm，by using the ROC curve to compare and evaluate the two kinds of dual-window detector performance used in SAR images.The results showed that the new method of detection had a better edge connectivity，the marginal error near the edge was less，and was sig? nificantly better than the rectangular bi-window detector.

Key words: rectangle bi-window, SAR image, edge detection, Gauss-Gamma-shaped bi-window