Abstract: As a kind of quasi-brittle material, concrete exhibits strain-softening behavior after the formation of micro-cracks. Based on the blunt crack band theory proposed by Z.P. Bazant, a 3-D softening constitutive relationship of rotating crack model is formulated. This crack model is then implemented into a finite element program and used for 3-D concrete fracture analysis under complex loading conditions. Numerical simulation of the single-edge notched shear beam by this crack model is compared with the corresponding experimental results and the one by fixed crack model. It is demonstrated that the 3-D rotating crack model herein can give more objective results in the analysis of mixed-mode fracture for concrete.