In a sense of engineering, composite laminary rockmass is considered as isotropic homogenitic rock element so that equal-effect constitutive theory and elast-plasticity theory can be used to derive the calculation equation for equal-effect elast-plasticity constitutive relation of composite rock-mass. A comparison between calculation results and test results of uniaxial co-mpressive strength indicates that they are in good agreement, thereby verifys the rationality and effectness of the mathematical simulation of this constitutive relation.