For a certain initial state of the Yunnan laterite and a certain slope, slope length,the effect of the physical and chemical properties of the Yunnan laterite on the erosion on slope under the f rainfall conditions is studied by using artificial simulated rainfall test method. The results indicated that:(1) The content of clay particles in the group of laterite is the most significant for slope erosion under rainfall effect. When laterite content increased about 8.1%, the erosion modulus increased by 25.8 g/(m₂.h);(2) The more the initial water content of laterite is deviated from the optimum water content, the erosion modulus of laterite became bigger. When the initial water content of laterite increased from 24.6% near the optimum water content to 30.5%, the erosion modulus increased from 110.4g/(m₂.h)to 121.3g/(m₂.h). (3) Under the conditions of initial dry density 1.0g/cm₃、1.1g/cm₃、1.2g/cm₃、1.3g/cm₃、1.4g/cm₃, the laterite erosion modulus was the change trend of the two curves which firstly increased and then decreased. At the initial dry density of 1.2g/cm₃, the erosion modulus reached a maximum of about126 g/(m₂.h).(4)The content of Fe₂O₃ and Al₂O₃ decreased by the effect of rainfall on the slope. The content of Fe₂O₃ decreased from 8.143% in the initial state to 8.591% and the content of Al₂O₃ decreased from 22.242% in the initial state to 20.967% on the surface of the slope foot. The content of Fe₂O₃ and Al₂O₃increased with depth in the slope. The content of Fe₂O₃ increased by 0.407%, and the content of Al₂O₃ increased by 0.861%. The changes of iron and aluminum oxide content will lead to the changes in the resistance to erosion of laterite .