Abstract: A flume is a hydroengineering building by which floating logs cross the dam of the hydropower station. Roughs are the device fixed on the bottom of the flume to regulate the drifting of logs. The purpose of this experiment is to find the optimum shape of the flume roughs.Two types of flume roughs are tested in our experiment, one in linear form and the other in the shape of "W" horizontally. Results show the linear form rough gives better hydraulic effect than the "W" shaped one.