The anisotropic properties of geomaterials are significantly related to their inherent microstructures.In this paper,a modified Drucker-Prager yield criterion for transversely isotropic materials is developed by evaluating the internal friction angle with the stress state,the microstructure tensor and the material principal direction.Then,based on the Cosserat continuum theory,a consistent return mapping algorithm for the modified criterion is formulated,and a consistent tangent modulus matrix is achieved.Moreover,the codes are implemented through the user defined element subroutine (UEL) in the finite element software Abaqus,and the correctness of the pro- gram is verified by comparing the theoretical results with the relationships of the material strength to the principal direction and anisotropic degree of the material in the integration points.Finally,the influences of the principal direction and anisotropic degree of the material on the bearing capacity and the failure mode of the structure are em- phatically analyzed by numerical examples,which are then compared with the results based on the classical contin- uum theory.It is found that the above-mentioned method is effective in simulating the strain localization of trans- versely isotropic geomaterials.