The influences of moss cover on detachment process of carbonate derived laterite in karst mountainous lands were explored and analysed. Undisturbed soil samples were collected and subjected to flow scouring in a 3.5 m long hydraulic flume. Two degrees of slope (5°, 20°) and two soil water contents (saturated soil water content, field capacity) were selected to quantify the relationship between moss coverage and soil detachment rate. The responses of hydraulic characteristics of slope runoff to moss cover were also analyzed. Compared to the field capacity, the results indicated that the detachment rate of saturated soil under moss cover increased by 33.9% and 10.8% at slopes of 5 and 20 degrees, respectively. The effects of moss cover on reducing soil detachment rate were more effective than that of bare soil without moss cover, and its effects were more obvious at lower slopes. The detachment rate under field capacity soil condition decreased in a linear trend with increasing moss coverage (R²>0.995). The moss cover had significant effects on the hydraulic characteristics of runoff flow at the slope of 5 degrees. The moss cover under saturated soil condition significantly changed the flow regime of surface runoff (P<0.05). Compared to bare soil without moss cover, the moss cover significantly reduced the runoff velocity (-20.6%), Reynolds number (-0.6%), Froude number (-28.6%) and runoff power (-0.8%), increased the runoff depth (+27.8%), flow shear stress (+26.9%) and Darcy-Weisbach resistance coefficient (+117.0%). Besides, the moss cover had no significant effects on the hydraulic characteristics of slope runoff at the slope of 20 degrees. Overall, no significant correlation exhibited between the hydraulic characteristics of runoff flow and the soil detachment rate of carbonate derived laterite covered with moss. These results can provide the experimental data for the study of applying moss cover to soil and water conservation in karst mountainous lands.