In automated 3D ultrasound imaging, effective ultrasonic signal can only be acquired if a good contact between the probe and the skin exists. To be able to achieve computeraided exclusion for areas where were uncoupled, a 2D image mask was generated in the coronal plane. Firstly, the average coronal images were obtained by averaging a series of 2D coronal slices which were continuous or intermittent. Secondly, the binary images were obtained by applying bimodal thresholding method on the coronal projection. The masks were obtained by applying morphology image processing method on the binary image, and choosing the best mask as the finally mask image. Finally, pending coronal plane image′s uncoupled areas were excluded by using the mask, and coupled areas were shown by applying pseudocolor processing. It is shown in the results that the proposed method achieves automated exclusion for areas without probe coupling of the automated 3D breast ultrasound (ABUS) data which can effectively avoid invalid operating of uncoupled areas in the subsequent image processing.