Abstract: Mechanical property data of canine cardiac muscle wereexperimentally obtained in the present study. In addition, finite elementsimulations were carried out for the uniaxial tension test and therelaxation test of canine cardiac muscle. The nonlinear elastic and viscousparameters of cardiac muscle are acquired to develop the nonlinearviscoelastic constitution of cardiac muscle for passive force. Furthermore, user material subroutine VUMAT in the finite element software ABAQUS is developed for the simulation of the numerical heart.