Abstract: Granite residual soils pervade the hilly and mountainous regions of Southeast China, where they are susceptible to destabilization and landslides, particularly under rainfall influences. These soils are classified into three categories based on particle size distribution: cohesive, sandy cohesive, and gravel cohesive. Their structural robustness significantly influences macroscopic slope stability through microstructural alterations. Advanced analytical techniques, such as X-ray diffraction and scanning electron microscopy (SEM), have elucidated the microstructural characteristics of these soils. The empirical data reveal that the cementation capacity and mechanical strength of cohesive granite residual soils are superior to those of the sandy cohesive soil. These microstructural properties play a pivotal role in determining the changes in macroscopic mechanical behavior of the soil. This research is of both theoretical and practical importance as it enhances understanding of the microstructural features of granite residual soils, their deformation mechanisms, and their impact on mechanical properties, offering valuable insights for geotechnical applications in forecasting and mitigating slope instability.