Conventional medical experiments can hardly simulate cardiac excitation propagation and observe the evolvement of cardiac electrical activities firsthand as is possible with computer simulation. Based on the anatomic structure of the heart, simulation of cardiac electrical activity mainly consists of the emulation of the excitation process among the cardiac cells and calculation of the electrical activities of individual cardiac cells. In this study we establish a geometric ventricular structure model demonstrating the direction of the cardiac muscle fibers and the layers of the ventricular cells, and endow different action potential models to the ventricular cells of different layers, and observe the activation process of the ventricular parts in view of the three-dimensional anatomy. This method gives attention to both enough calculation amounts and efficiency, which achieves satisfactory simulation results of ventricular electrical activity based on the anatomic structure and cell electrophysiology through an improved algorithm on personal computer.