The relationships for hydro-dynamic parameters(Reynolds number,Froude number,resistance coefficient and flow velocity) of overland flowas a function of bed roughness,flow discharge and slope gradient were simulated by means of indoor fixed-bed resistance experiments.The preliminary result indicates that Reynolds number and Froude number of overland flowtend to increase as slope gradient increases in the condition of same bed surface and flow discharge.Reynolds Number and Froude number of overland flow tend to diminish,water flow velocity tends to diminish,and resistance coefficient tends to increases as bed surface roug hness increases in the condition of same slope gradient and flow discharge.It shows that consumed energy for working of water flow against resistance tends to increase.