Abstract: Slope erosion is one of the main sources of sediments in middle and upper reaches of the Yangtze River. The quantitative study of soil detachment process in middle and upper reaches of the Yangtze River has an important theoretical and practical significance in revealing soil erosion mechanism and preventing and controlling the soil and water losses. The scour experiment in this paper was carried out in a flume with a variable slope. We studied the relationship between soil detachment rate and slope, flow quantity and other main hydrodynamic parameters, aimed to find out the optimal parameters which can better simulated the soil detachment process. The results show that the soil detachment rate is positive correlated with flow quantity, slope and multiple hydrodynamic parameters. The power exponents of slope and floware all greater than one, indicate that these two parameters have a superimposed increasing effect on soil separation rate in the determination range. The coefficient of determination between stream power and soil detachment rate is the highest (R2=0.93), which means that more effective information can be obtained when using stream power to fit soil detachment rate. When unit stream power is larger than 0.280 7 m/s, the soil detachment rate begins to increase.However, the calculation of runoff shear stress (R2=0.83) only needs slope and depth as input parameters. The calculation of stream power value should not only rely on data such as slope and water depth, but also need data such as current velocity that relatively difficult to obtain.Therefore, it is more convenient to use the runoff shear stress to fit the soil detachment rate than using the stream power, but using stream power to fit the rate of soil detachment will be more accuracy.