The invention relates to a cardiac medical image processing method, a processing device, a processing system and a medium. The method comprises the following steps: receiving a cardiac medical image of a left ventricle long-axis section; utilizing the trained first learning network to identify mitral valve base points and apex apexes on two sides of the left ventricle and the outer edge and the inner edge of the left ventricle myocardium; arranging an upper edge by utilizing a first connecting line of a mitral valve base point; defining the left ventricular myocardium by the upper edge, the inner edge and the outer edge, using the midpoint of the first connecting line and the second connecting line of the apex of the left ventricular as the midline, evenly dividing the parts, on the two sides of the midline, of the left ventricular myocardium into n parts, and therefore the left ventricular myocardium is divided into 2n sections. According to the cardiac medical image processing method, the processing device, the processing system and the medium, each cardiac muscle area can be automatically, accurately and quickly drawn and identified, the workload of doctors is greatly reduced, and automatic identification of the cardiac medical image processing device can continuously benefit from a training data set marking the cardiac muscle areas through training.