Abstract: To obtain brittle shear character parameters, acoustic emission accompanied with triaxial stress-strain test was applied to monitor the initiation and expanding of micro cracks in rock material. Theoretical analysis and data processing were carried out based on the theories of fracture mechanics and general rock mechanics, relations between the feature strength of three stages and the stress state were obtained, and a method was proposed for analyzing the brittle shear failure of rock material. The relationships of the Mohr-Coulomb strength theory, Griffith strength theory and Hoek-Brown criterion with the brittle-shear coupled strength model were discussed. Strength analysis of mixed granite in Shuichang slope was carried out by the brittle shear failure model, and the result of comparison shows strong correlation between test data and theory values.