Weirs are used to control flood flow, to regulate water level and to measure flow discharge in hydraulic systems. These hydraulic structures are typically made of concrete, having an impermeable build, thereby flow just passes over their crown. By placing an impermeable weir across a river, the aquatic ecosystem is affected and suspended materials movement toward the downstream is prevented. Therefore, these weirs have many negative effects on the downstream environment. In contrast, gabion weirs with some merits including sustainability, permeability and cost-effectiveness are of the suitable hydraulic structures to meet the stated objectives. These weirs are structurally stable and resistant to loads caused by great values of approach flow discharges, having favorable efficiency of flow energy dissipation. These weirs can be installed and operate in various forms in the rivers and canals. To increase the length of the weir crest, they can be used obliquely in respect to the approach flow direction. Due to the increase of the effective weir crest length, the overflow discharge over the oblique weirs increases and the hydraulic aspects of flow such as the discharge coefficient are improved. On the basis of the improved features and benefits of gabion weirs as well as the increased performance of oblique weirs compared to the frontal normal weirs, the present study investigates the hydraulic characteristics of flow over oblique gabion weirs with different geometries. The purpose of this study was to investigate the effect of different geometrical and hydraulic parameters on the discharge coefficient, threshold submergence depth, and energy loss. For this purpose, 12 Gabion weir models were installed in a flume of 11 m long, 0.4 m wide and 0.7 m deep, in the hydraulic laboratory, department of civil engineering, Isfahan University of Technology, Isfahan, Iran. This investigation covers different materials with average diameter of 11, 16 and 21 mm with porosity of 0.33, 0.35 and 0.39 and oblique gabion weirs with different downstream angles of 0, 30, 45 and 60 degrees in respect to a vertical direction. The oblique weirs angles were 0, 30, 45 and 60 degrees in respect to the approach flow direction, with the crest widths of 50, 100 and 150 mm and the heights of 100 and 200 mm. The effects of each dimensionless parameter on flow discharge coefficient, energy loss and threshold submergence depth was investigated. Results show that by increasing the angle of obliqueness the flow discharge coefficient decreases and the energy loss and threshold submergence depth increase. However, by increasing this angle, the flow discharge increases. For the gabion weirs, as the aggregates size and the porosity increase, the overflow discharge coefficient increases and the threshold submergence depth and the flow head loss decrease. Generally, the discharge coefficient and the flow energy loss of gabion weirs are both greater than those of impermeable weirs. The influences of other geometrical parameters were also studied in detail and finally, by applying the software, different relationships were derived for estimation of the flow discharge coefficient, flow head loss and threshold submergence depth. Keywords: Discharge coefficient, free flow, threshold submergence depth, energy loss, gabion weir, oblique weir.