The sharp-crested weirs are widely applied in agricultural and hydraulic engineering for the purpose of measuring and regulating flow. These weirs consist of various shapes with special characteristics. This study is concerned to introduce a new kind of sharp-crested weir with sinusoidal notch. Physical models of sinusoidal sharp-crested weirs, containing different widths and heights, were constructed and investigated. It is found that the theoretical head-discharge equation includes Fresnel sine and cosine integral. For simplicity and considering practical purposes, the integral parts were removed from the original equation without loss of generality. Analyzing the experimental data showed that the discharge coefficient of sinusoidal weir can be assumed as a constant (about 0.57) for the complete developed head-discharge equation. In contrast, the discharge coefficient of the truncated head-discharge equation presents a periodic trend with the head over the crest. The results indicated that the basic trends of velocity profiles of the sinusoidal and rectangular weirs are mainly identical. But the dimensionless longitudinal velocity (Vx/V1) of sinusoidal weir is less than that of rectangular weirs due to the wider notch of sinusoidal weirs for the same crest width. Conversely, the variations of secondary currents at the sinusoidal weirs are more than rectangular weirs, especially for higher heads and sinusoidal weirs with more cycles.