In order to reduce such effects of interference as microscopic structure,noise and weak edge on theimage edge detection and to improve the positional accuracy of the detection,an edge detection method is proposedon the basis of edge intensity accumulation characteristic in scale- space.This method selects the optimal scale oftarget edges by comparing the average edge intensity of target object at different scales,and then filters out all thejamming edges at the optimal scale according to the difference of edge intensity accumulation values of edge pointsin scale- space.Experimental results show that the proposed method can effectively restrain all the above interferenceswith slight smoothing,and thus the stability and positional accuracy of target edges is improved.