This paper presents a computational fluid dynamics (CFD) simulation to investigate the effects of the obliqueness of cylindrical weirs on the flow velocity distribution, the pressure distribution and the distribution of water depth over the weir crest. Three different cylindrical weirs with diameters of 0.114 m, 0.09 m, and 0.0635 m, with three dissimilar inclination angles of 90°, 135°, and 150° were used. The SSG Reynolds stress turbulence closure model was utilized in the analyses. The results show that the flow patterns are affected by the inclination angle with respect to the flow direction. It was noticed that inclination angle increment increases the velocity of flow at the downstream surface of the weir, thus increases the absolute value of the negative pressure, at the inward-moved end of the weir. The outward-moved end of the weir was observed not to be covered with water and extending with the increase of the inclination angle.