Abstract: It is important to judge reasonably the failure modes and their corresponding strength in the engineering analyses of rock mass. Due to the existence of the weak planes of joints in the Complex rock mass, the failure modes and strength are affected by the structures and the stress states, and characterized by the anisotropic properties. But the proper attention is not yet paid to this problem. Based on the theoretical analyses and experimental data, the two- and three-dimensional theoretiS 1modes and the failure criterions, which considered the influence of the weak planes of joints, are presented. The simulating tests and the nonlinear finite element analyses of the two-dimensional problems are carried out,and the comparisons between results of tests and computations are introduced.Finally, the anisotropy of the failure modes and strength and the use of FEM are discussed and analysed.