Directed against uneven illumination of image，this paper proposes a threshold image segmentation algorithm based on edge detection.According to this method，the continuity of spatial distribution of the objects，background and the illumination has been considered to determine the threshold by using the information of the edges gradient.Then，the average of the maximum and minimum value near the edge detected by edge detection algorithm is used as the local threshold for the pixels on the edge.Using surface fitting，the threshold surface is constructed by the edge-threshold control points for image segmentation.The experimental result shows that the algorithm is efficient，and its Edge-Border Coincidence is higher than other typical algorithm.The ability of Anti-fuzzy of this algorithm is stronger and it has overcome the weakness of the edge-based method which is easy impacted by noise.