Based on our previous electrical heart model, an electromechanical biventricular model was constructed by means of composite material theory and the finite element method. And the 3-D motion of the right ventricular wall was simulated based on this model. The orientation of cardiac fibers and myocardial contractility were taken into consideration during simulation modeling. The propagation of electrical excitation was simulated using an electrical heart model, and the resulting active forces was used to calculate the ventricular wall motion. Regional deformation and Lagrangian strain tensors were calculated during systole. Displacements, minimum principal strains were used to describe the motion of the right ventricle. The simulation results are in good accordance with results obtained from MR tagging images reported in literatures. In addition, the results also show that although the maximum displacement occurs in the base of the heart, however, the maximum contraction occurs in the apex of the heart. Such result is very difficult to be obtained by means of animal experiment or human experiment. This study suggests that such electrophysiologic-mechanical biventricular models have the important significance to be used to assess the mechanical functions of the two ventricles.