Because of the existence of image noises, classical edge detection operators often fail to detect the edge exactly in many cases.In view of this, we analyze the geometry characters of edge under the condition of noises, and propose an enhanced algorithm of Canny operator, based on geometry edge enhancing.The algorithm firstly applies Canny operator to compute initial edges, and then excludes weak edges according to an automated threshold.In the following, it computes the directed gradients of remaining edges to improve the edges, and computes the double thresholds according to the improved edges.Finally, this algorithm detects filters and connects the edges by the double-thresholds method.This algorithm improves the accuracy of the edge detection, and can handle the false edges caused by noises or textures efficiently.