Based on the law of soil water movement in the unsaturated zone, the study discusses the effect of preferential flow on the movement of the researched soil through a soil column experiment using homemade experimental apparatus in four successive stages-young, middle-aged, mature and over-mature and combining dye-tracer analyses of the field process. The study proves that preferential flow occurs in that area, and as indicated by the Reynolds numerical calculation of the preferential flow path in the four different successive stages, the preferential flow in the Gongga mountain forest ecosystem is the transition flow between laminar flow and turbulent flow. The study applies the kinetic wave model with dispersion wave (KDW preferential flow model), and by inspecting and comparing this model with the field experiment, finds the preferential flow model has good practicability and high credibility. Verifying the KDW preferential flow model through statistics analysis, the results indicate that the model can simulate the water movement in columns very well and that the results are better in low rainfall than in high rainfall. Analyzing the effects of the KDW preferential flow model on runoff, the results indicate that preferential flow moves via kinetic wave and dispersive wave, of which kinetic wave is dominant. Combined with the fact that the soil water movement is mainly in the preferential flow path, we observed that preferential flow is the main path of matter movement in soil, which produces an important effect on the formation of watershed runoff and flood peak and provides the main source of underground runoff as well.