A series of overland flow experiments were conducted by changing slope degree including 15 degrees, 20 degrees and 25 degrees on the smooth and adhering sand slope (shown in Fig.1), the hydraulic parameters including velocity and depth have been measureed in different slope locations and flow discharges, furthermore, the resistance characteristic of thin layer in overland flow has been also discussed according to the average Weisbach-Darcy coefficient method and the improved calculating method considering the variations of hydraulic factors along slope distance.