<p>Fractures in surrounding rocks of underground engineering significantly weaken the mechanical properties of rock masses, thereby threatening the overall stability of the structure. The fracture geometry largely governs the mechanical response and crack propagation characteristics of rocks. Granite specimens prepared with pre-fabricated cracks were subjected to a series of uniaxial compression experiments to systematically examine the combined effects of fracture length and inclination angle on key mechanical indicators. The integration of acoustic emission (AE) monitoring with digital image correlation (DIC) was adopted for coupled analysis from both microscale temporal characteristics of crack activities and macroscale spatial evolution of crack propagation. The results demonstrate that both peak strength and elastic modulus exhibit an initial decline and a later rise as the inclination angle increased. Inclination angle exerts a pronounced influence on the crack initiation angle. Tensile fractures are the predominant mechanism of failure in pre-fractured granite. The RA/AF point distribution density is highest for specimens with 45° fractures, whereas it is lowest for those with 90° fractures. The staged evolution of DIC grayscale histograms and variance during loading indicates that abrupt increases in grayscale variance can function as an early-warning signal for predicting rock failure. Furthermore, in-depth analysis reveals that the sharp drop in AE <i>b</i>-value curves (processed via fast Fourier transform filtering) coincides well with the abrupt increase in DIC grayscale variance, highlighting their consistency in predicting rock failure. The findings provide new insights for failure prediction and stability evaluation of fractured rock masses with complex fracture geometries.</p>