The fuse plug is used as a safety valve to protect the dam from catastrophic failurs caused by overtopping flow. In this experimental study, using a series of experimental tests, the effect of plug fuse washout on the outflow discharge from the dam reservoir due to change the width and depth of the pilot channel has been investigated. The important point in this study is to be kept constant water level during the overtopping flow and the failure of the structure for the more similarity of this process to reality. The results of this experimental study are the outflow hydrograph resulting from the overtopping flow the change in width and depth of the pilot channel. Also, the effect of changes in the outflow discharge more dependent on the depth of the pilot channel than the pilot channel width, in such a way that the pilot channel width changes can be ignored within the range of parameters in this study. Hydrograph and non-dimensional relations for the outflow discharge from the embankment have been presented. According to the obtained results, the optimum depth and width of the pilot channel were determined.