<p>As one of the most catastrophic types of soil erosion, collapsing gully erosion with an extremely high sediment transfer rate has caused extensive soil loss and land degradation in southern China. The disintegration of granite residual soil (GRS) is widely acknowledged to be decisive for the formation and development of collapsing gully erosion. However, how soil particle composition—the most basic but no less important soil property—influences the disintegration behavior of GRS is yet to be clarified. In this study, systematic disintegration tests were performed on natural GRS obtained from various depths as well as reconstituted soil with different particle compositions, thereby establishing how the particle composition controls the disintegration of residual soil. The test results show that the particle composition affects the disintegration behavior of natural and reconstituted GRS differently. While it dominates the disintegration of reconstituted soil, with coarser particle composition corresponding to less-stable behavior, particle composition is not the critical factor for natural soil. Instead, the relic structure inherited from the parent rock plays an essential role via the interparticle cementation associated with iron-bearing minerals as well as the fissures formed by mineral leaching. Also, the effect of soil structure is quantified and found to correlate well with the disintegration parameters. This study provides new insights for soil erodibility evaluation, showing that the importance of soil particle composition has seemingly been overstated for natural residual soil from highly eroded areas and that the soil structure should receive more focus.</p>