Abstarct: Study of bed Scour Downstream of hydraulic structures considering to the imposed costs, has special importance. For this reason, it has always been a matter of interest to various researchers, and throughout the world researchers investigate this phenomenon and its control strategies. Among the hydraulic structures, sluice gates can be pointed out So that the scouring downstream of them in addition to financial costs, changes the morphology of bed , will lead to problems in the impoundment process in the downstream. Therefore, in the present research, an experimental study of scour dimensions, such as length and height of peaks on the downstream of sluice gate carried out. The laboratory flume had 5 m long, 0.09 m wide and 0.34 m height and it was sloping. The geometric and hydraulic parameters considered in the experiments were 3 slopes (0, 0.5 and 1%) with three roughness heights (0.75, 1.5 and 3 cm), roughness distances (0, 1.5 and 3 cm), and four rates (6.5, 5, 3.5, 2 m3/hr). According to the obtained results, variations of the scour dimensions in the early times of the experiments were high and then decreased gradually with approaching the end of the experiment times. Also the dimensionless longitudinal profile of scouring increased so that for a constant opening as increasing the flow rate, the scour length increased so that the more opening of gate, the slope of length changes is less. The results also showed that with increasing the Froude number, the Ls/b (scour length to flume width ratio) increased and best performance in reduction of Ls/b was related to a roughness size of 1.5 cm, which reduced the Ls/b about 33%. Increasing the roughness size also increased the performance in controlling the Ls/b, for roughness size of 1.5 cm, reduced Ls/b about 75%. Also, with increasing w/b (opening to flume width ratio), the Ls/b also reduced which the range of its variations for roughness of 1.5 cm was in the range of 1 to 5. As increasing the slope (S) the value of Ls/b for different roughness distances increased. Also results showed that, the range of Ls/b variations against S, for less gate opening was minimum. Also with increase of d/b for different openings, the value of Ls/b reduced, so that at the maximum opening of the gate, the value of Ls/b reduced about 37% relative to the flat bed. Also Variations of hs/b (peak height to flume width ratio) was low for different models and was about 0.5. By increasing the gate opening, its fluctuations were less and with decreasing the opening, its fluctuations were more.