A method of watershed segmentation based on morphological gradient reconstructing was proposed.First,morphological gradient image was obtained.Second,opening and closing by reconstruction operators were employed to reconstruct gradient image,and then standard watershed transformation was used to implement image segmentation.Through gradient image reconstruction,important region contours are preserved while most small regular details and noise are removed.The over-segmentation of the standard watershed segmentation is avoided and the region contours bias caused by the traditonal method with opening and closing to smooth original image followed by the standard watershed segmentation is also eliminated.Simulations show that the method can efficiently eliminate over-segmentation,and hold the position of region contours without evident bias,also the method can produce good segmentation without post-segmentation processing,which in some degree reduces the complexity of the segmentation.The whole segmentation needs only one parameter,disk-shaped structure element,which is convenient to adjust to different applications.