Duckbill weirs have not a straight crest in the perpendicular direction to the flow. The plan view of the weir consists of multiple and broken linear crests that cause the increase of its effective length. The advantages of this type of weirs are higher discharge capacity, easy aeration as well as low fluctuations of water surface at the weir upstream. This paper deals with the simulation of the flow over duckbill weirs with triangle plan form to obtain its discharge coefficients. In order to simulate the flow over the weir, fluent software was used as a virtual laboratory. The turbulence and the free surface of the flow were modeled by k-ε RNG and volume of fluid (VOF) algorithms, respectively. The results were compared with the experimental results of Kumar et al. (2012) for curved plan crest duckbill weir. The comparison of the results indicated that the curved plan form weirs have the higher discharge coefficients (1.25 times the discharge coefficient of in triangular plan form for θ = 45◦) than the ones in triangular plan form. Also duckbill weir with triangular plan form in low hydraulic heads  has good performance and the discharge coefficients are in a satisfactory range.