<p>Soil-rock mixture (SRM) landslides are prevalent in nature, necessitating further investigation into their inducing mechanisms. In this study, a coupled numerical approach integrating the Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) is employed to investigate the evolution of deformation patterns and failure mechanisms of SRM slopes induced by rainfall, from both macroscopic and microscopic perspectives. The results indicate that: (1) The presence of coarse blocks leads to the development of multiple slip zones within the SRM slope, and a significant ‘rock-bypassing effect’ is observed during the failure process; (2) When the block content is below 50%, a limited number of coarse blocks may accelerate the initiation, propagation, and coalescence of cracks, negatively impacting slope stability. In contrast, when the block content exceeds 60%, the interlocking effect of the block skeleton effectively suppress crack development, thereby enhancing the stability of SRM slopes; (3) From the perspective of micromechanical failure mechanisms, the coupled action of fine particle migration and erosion, along with structural damage to the block skeleton is identified as the primary cause of SRM slope instability; (4) Rainfall primarily promotes slope failure by intensifying the migration and loss of fine particles, weakening the interlocking between skeleton particles, and reconstructing the force chain network, ultimately transforming the failure mode from localized erosion to global sliding instability. The research findings offer valuable insights for the prevention and mitigation of soil-rock mixture landslides and provide a methodological reference for analyzing the macroscopic mechanical behavior of discrete geotechnical media from a mesoscopic perspective.</p>