Abstract: Based on the displacement, a reverse analysis of object function was set up. According to the actual measuring displacement, the elastic modulus E and Poisson ratio μ of soil and rock were directly computed by using boundary element method and simplex method. As the measuring displacement was the cooperative result of rock structure and applied force, the complicated rock could be considered as a comprehensive elastomer in the process of the reverse analysis. The compound parameters E and μ could reflect rock structure and provide a basis for engineering computing.