It is important to assessing the causes for Failure of Ayrara Irrigation Scheme in Ankober wereda. Hydraulic, hydrologic, and structural analysis of Ayrara irrigation project were analyzed using hydrological model, hydraulic computation, and structural analysis tools respectively. ARC-GIS 10.5 employed for watershed delineation. Both primary and secondary data were collected. The hydrology analyses made by SCS and HEC-HMS software by using daily annual maximum rainfall of Ankober metrological station. The structural analysis involves checking stability analysis of the weir against overturning, sliding, and shear the weir. From the hydrological analysis result, the design was 160.5m3/s but in the design document, peak flow was 120m3/s. On the other hand, HEC-HMS 4.8 the result showed that the design flow was 153m 3/s, which is equivalent to hydrological analysis. Hydraulic design document evaluation indicated that, the project had not under sluice, energy dissipaters, river training work, cutoff and the right side of the abutment have no appropriate drainage and retaining wall. The structural analysis result indicated that stability factors against overturning, sliding, and shear calculated values lower than the recommended value, which is triggering to failure (unstable). From the geology report and during site observation, there was high sediment accumulation on the right side of the weir that coming from monotonous upland watershed during summer. Finally, the failure of Ayrara weir related to peak flood estimation, absence of appropriate drainage systems and absence apartness hydraulic structure like energy dissipater and under sluice, absence of upstream and downstream cutoff, absence of retaining wall, instability. For sustainability of any hydraulic structure, designer should double check their hydrologic, hydraulic, and structural analyses parameters before construction.