A new algorithm for medical image edge detection is proposed based on multi-structure element morphology.Four different edge detection results are gotten by using the multi-structure elements with the anti-noise morphology gradient respectively,which is derived from the open and close operations.And then we adopt the quad-decomposition characterized by mean and standard deviation to enhance the thin edges.The performance of the new algorithm is analyzed and proved both on theoretical and stimulation results.Experimental results show that the new algorithm are more efficient for image denoising and it can preserve more edge details in the dark region than those traditional edge detection algorithm.