For studying the relationship between preferential flow and surface runoff

a natural second Chinese pine (Pinus massoniana) forest in the area

which has not been heavily influenced by people

is selected as an experiment site. The process of preferential flow has been recorded by an automatic flowmeter during the time of the experiment. The soil physical properties have also been determined at the same time. The result shows that the discharge of the preferential flow is mainly influenced by the precipitation and the ante~precipitation. The appearance of the preferential flow peak is later than the peak of the surface runoff. The preferential flow defers the appearance of the peak of the surface runoff and prolongs the surface runoff duration. It is not obvious that the preferential flow appears linear relationship with the surface runoff when both the preferential flow and the surface runoff appear two peaks at the same precipitation. On the contrary

the linear relationship between the preferential flow and the surface runoff is marked while both of them have one peak

and it changes with the variation of precipitation and ante-precipitation.