The invention discloses a segmentation method and device for a heart image. The method includes that a layer of heart computed tomography (CT) image between the bottom and the upper part of a heart is searched among all layers of scanned heart electronic computer X-ray tomography images to serve as a first critical layer; the boundary of the heart is searched on the first critical layer to serve as a heart bottom outline, and a surface model is generated according to the heart bottom outline and a heart bottom lowest point to serve as a heart bottom model; the boundary of the heart is searched on all layers of heart CT images above the first critical layer to serve as a heart upper part outline, and a surface model is generated according to the heart upper part outline to serve as a heart upper part model. According to the segmentation method and device for the heart three-dimensional image, the segmentation accuracy can be guaranteed, segmentation calculating amount and complexity can be reduced as far as possible, and image segmentation can be rapidly achieved.