The use of a two-flow domain model improves description of soil solute breakthrough curves, especially in preferential flows. But all parameters of the model currently can only be figured out by the inverse method, thus restricting its application. In recent years, development of the capillary theory and the model of soil hydraulic property make it possible to expose mechanisms of soil water and solute movement from a more microcosmic angle, and use a new method to determine parameters of the convection-dispersion model. Based on the Brooks-Corey model, pore velocity distribution is deduced from soil water suction curve in this paper, relationship between the geometrical coefficient of the Brooks-Corey model and the parameters of the two-flow domain model established with the average pore velocity set as the critical velocity between the two flow domains, and hence a method for determining parameters of the two-flow domain model proposed in this paper. Data measured in field observation are used to test the reliability of this method either considering immobile water in soil or not. The results indicate that the predicted breakthrough curves are far from the observed without taking into consideration immobile water;and quite close to the observed with immobile water taken into account. Errors would not be too great for loam soils and sand loam soils in the prediction based on the two-flow domain model, and the model parameters determined through the method proposed above.