It was the fundamental purpose of controlling agriculture no-point pollution to reveal the mechanism of substrate soil solute transported in runoff.To analyze the hydraulic characteristics of overland flow and parameters of soil solute in runoff

the Hydro-dynamic properties of soil solute in runoff on different loess slope was studied in this paper.The aim of study was to go deep into understanding the mechanism of soil solute transference in runoff.The result showed that the quantity of soil solute in runoff had relation to the ratio of roughness coefficient to averaged flow depth on different loess slope.The mean concentration of soil bromide in runoff

the average losses rate of soil bromide in runoff and the relative losses of soil bromide in runoff each of them decreased as the ratio of roughness coefficient to averaged flow depth increased.Both the data for the average losses rate of soil bromide in runoff and the relative losses of soil bromide in runoff to the ratio of roughness coefficient to average flow depth(n/h) respectively fit the form of an exponential curve under the different loess slope.