The variations of hydro-dynamic parameters(Reynolds number,Froude number,average flow velocity,water depth and resistance coefficient) of overland flows were characterized under different flow discharge,slope gradient and roughness based on flume experiments.The research results indicated that Reynolds number,Froude number,average flow velocity,water depth and resistance coefficient of the overland flows increased with flow discharge for the artificial beds with same roughness and slope gradient.Under the conditions of same gradient and flow discharge,Reynolds number,Froude number and average flow velocity of the overland flows decreased with increasing roughness,while resistance coefficient and flow depth increased.Flow discharge and slope gradient were found closely correlated with the hydraulic parameters such as average flow velocity,water depth,and resistance coefficient,which could be well described by simple power functions.Furthermore,the influences of flow discharge were dominant.