Abstract: For studying the soil erosion modulus in the Karst rocky desertification areas,the measurement method of the sedimentation at the deposition zone of basin is used to calculate the soil erosion modulus and to speculate on the rocky desertification process of the Mawoshan of Wumeng range in the Karst area.The environmental effects on the soil erosion modulus,caused by human being's activities in Karst rocky desertification areas are discussed simultaneously.The research results indicate that the soil erosion modulus in the Mawoshan is very high,up to 2 900.55 t/(km²·a),which can reflect the position of the soil erosion objectively in the karst rocky desertification areas.Considering nothing but total quantity changes in the process of calculating the soil erosion modulus,the measurement method of the sedimentation at the deposition zone should be choiced firstly for the soil erosion calculation in the Karst rocky desertification areas where there is no observation data and survey station.