Geometrical active contours (GAC) are used extensively in computer vision and image analysis, particularly to locate object boundaries. However, GAC-based segmentations have the drawbacks of long evolving time and boundary leaking. Because halting speed fields (HSF) in GAC models are typically not smooth enough in homogenous region, they are not able to make the active contour quickly move towards the desired object boundaries. On the other hand, the HSF don’t really vanish along the object boundaries, thus the curve propagating can not stop on the object boundaries and continuously move into the object boundaries (boundary leaking). In this paper, an anisotropic diffusion model is therefore presented and then applied to the HSF in GAC model. This GAC-based segmentation with the diffused HSF can overcome the two drawbacks above. Experimental results on a synthetic image and two real world images show the improvements in terms of reducing both the segmentation time and boundary leaking, in comparison of GAC model with the original HSF.