Cylindrical weirs- gates are one of the combined structure types which have advantages such as low cost, simple design, easy construction and the high discharge coefficient. In this study, the cylindrical weir- gate location in perpendicular orientation to flow direction on discharge coefficient have been investigated experimentally. The experiments were conducted in a flume with the length of 7.5 m and width of 40 cm, using the cylindrical models were made up of plastic pipes with diameters of 50, 75, 110 and 125 mm. Experiments were conducted with different gate opening heights from 0 to 60 mm (reaching to the cylindrical gate by considering the available diameter and discharge). The results show that the maximum and the minimum discharge coefficient has been observed in the cylindrical weir and cylindrical gate, respectively. Moreover, by substituting the cylindrical weir- gate with cylindrical gate, the curves depicted amount of against the ratio of upstream flow depth to the cylinder diameter ( ) and the ratio of difference between upstream and downstream flow depth to the cylinder diameter ( ) has reduced suddenly, which this progress was due to decreasing the amount of backwater and remarkable decreasing in upstream depth. Furthermore, increasing in amount of cylindrical structure diameter leads to decrease in discharge coefficient. The best correlated relations for quantifying the behavior of discharge coefficient , were proposed.