Abstract: A method of multi-scale object extraction and segmentation based on morphological opening and closing by reconstruction is proposed.Top-Hat and Bottom-Hat transformation based on reconstruction with SE(structure element) nB are applied to image to get all objects which can not put into SE nB.Then objects smaller than(n-1)B are removed by opening reconstruction.So the remain objects can only hold SEs smaller than(n-1)B but not nB in the result image.Segmentation of various scale result images can get different scale object's counters.Reconstruction is an operator based on connected region which can exactly preserve the boundaries and edges of image and do not create spurious extrema.