The complicated occurrence of two-dimensional (2D) and three-dimensional (3D) fractured structures has an important influence on the initiation, propagation, and fracture of rock secondary failure. The brittle gypsum rock-like samples were prepared for the uniaxial compression test in this work, accompanied by the acoustic emission and digital image correlation technologies for monitoring the failure process. The following main conclusions are obtained: 1)Under the uniaxial compression condition, the 2D crack propagation shows a typical mode. With the increase of compressive stress, the wing crack grows along the bending path and then gradually expands in parallel with the principal stress direction, forming the tensile failure of the “wing crack”, which dominates the surface strain field and the distribution of secondary cracks. At the same time, the local failure of the 3D crack appears earlier and remains concealed. 2)Acoustic Emission (AE) monitoring analysis shows that the first AE outbreak is dominated by high-intensity tensile failure ; in the final explosion stage, the tensile failure is slightly more than the shear failure, and the tensile failure is dominant in the test. 3)The sampling window and step size selected in the calculation of the b value directly affect the evaluation results. The sensitivity analysis results show that the fine grouping can better retain the extreme value and facilitate the prediction of instantaneous severe damage. 4)The conclusion of the previous 2D simplified study of cracks is not applicable to the 3D environment of cracks. The existence of fracture structure and the underestimation of density will overestimate the strength of rock, so there are potential safety hazards in practical engineering.