【Objective】Collapsing hills are widely distributed in granite-covered areas of tropical and subtropical South China, characterized by being high in erosion rate, strong in explosiveness and difficult to control. Colluvial deposits, formed of materials accumulated at the foot of the collapsing wall, are an important component of a collapsing hill, and meanwhile as they are loose in texture, high in content of coarse particles and high in erodibility, they become the main source of erosion sediment in the area. The erosion of colluvial deposits has aroused widespread attention, however, the current study on colluvial deposits still has some shortages. For instance, so far nothing has been reported on characteristics of the disturbed soil of colluvial deposits and laws of the erosion thereon.【Method】Therefore, to study properties of erosion sediment from colluvial deposits, an indoor rainfall simulation experiment was carried out on slopes of colluvial deposits, 30° in gradient, different in coverage (0, 25%, 50%, 75%, 100%) and different rainfall intensity (60, 90, 120 mm h^-1), SPSS18. 0 was used to analyze relationships of the characteristics of particlesize composition with coverage.【Result】Results show as follow: (1) The mean content of coarse sand was much lower, and the mean content of fine silt much higher than that in the test soil. During the process of rainfall，runoff on the slopes carried long with it soil, particles small in size first; The mean enrichment rates of fine sand, coarse silt, fine silt and clay were all higher than 1 in the sediment. (2) The content of coarse particles (gravel and coarse sand) reduced first，then rose again and the content of fine particles (fine sand, coarse powder, fine silt and clay) did not very much with increasing coverage. (3) On slopes, varying in the range of 0~25% in coverage, the content of fine particles reduced slowly, while the content of gravel and coarse sand rose gradually with the rainfall going on; on slopes 50% in coverage，the content of fine particles remained high, while the content of coarse particles stayed low throughout the rainfall event; and on slopes reaching 75% in coverage, the content of soil particles various in size fluctuated sharply during the course of a rainfall event, and in this case, collapse of the slopes occurred readily. (4) And the mean weight diameter (MWD) of the erosion sediment decreased first and then increased with increasing coverage. 【Conclusion】MWD of sediment particles was found to be significantly related to coverage of the slope, rather than rainfall intensity. When the coverageof the slopewas around 50%, the effect of sediment reducing was better. Therefore, in the process of prevention of erosion, we should pay attention to the control of the coverage on slopes.