<p>This study combines laboratory variable-angle shear tests and numerical simulations to investigate the mechanical behavior of flawed granite specimens containing two parallel fissures with limited length at different shear angles (55°, 60°, 65°, 70°) and dip angles of fissures (0°, 30°, 60°, 90°). The PFC grain-based model (PFC-GBM) combined with the spatial coordinate transformation matrix was employed to simulate variable-angle shear tests and to analyze shear strength, crack evolution and coalescence, and the associated force-chain, displacement, and stress-field responses. Results show that increasing the shear angle leads to a significant reduction in peak load, a decrease in total crack number, and a transition in failure mode from “crushing” to shear-dominated. The influence of dip angle on shear strength exhibits a non-monotonic trend, with the highest shear strength at 30°. Crack type analysis indicates that both the count and the fraction of intragranular tensile cracks among all crack types decrease significantly with increasing shear angle, while the fraction of intergranular tensile cracks increases. The distribution of force chains and the second invariant of the stress tensor reveal the formation mechanism of the main failure band. Numerical simulations accurately captured the laboratory response with good fidelity, reinforcing the mechanistic interpretations presented here and elucidating how changes in shear angle and dip angle of fissures drive the shift from tensile-dominated cracking to shear-band formation and force-chain redistribution in flawed granite.</p>