This thesis presents an enhanced nodal-based discontinuous deformation analysis (NDDA) based on the coupling of the discontinuous deformation analysis (DDA) and the finite element method (FEM), for modeling blocky systems, especially for simulating crack propagation in rock mass. The NDDA can provide a more accurate stress and strain distribution in each block and has a higher computational efficiency than the standard DDA in dealing with continuum materials. Furthermore, the enhanced NDDA allows for tensile and shear fracturing happening inside an intact block, which provides a way for material transforming from continuum into discontinuum. A computer program named 2D-NDDA was developed to handle the combination of continuous and discontinuous in large displacement problems, as well as large deformation and failure analysis, under external loads and boundary conditions.