Abstract: A new type of breakwater structure, semi-elliptic breakwater, is proposed. The numerical wave flume is established by FLOW 3D, and the interaction between semi-elliptic breakwater and waves is simulated. The rationality of numerical model is proven by physical model test. Combined with numerical simulation results, the influence of wave parameters on hydrodynamic characteristics of semi-elliptic breakwater is analyzed. The results show that the reflection coefficient increases with increasing h_s/H, the transmission coefficient decreases with increasing h_s/H. Within the range of wave period, when D is constant, the wave retaining effect of semi-elliptical breakwater with larger wave period is better than that with smaller wave period. With the increase of D/b, the wave retaining effect becomes worse. The wave force increases with the decrease of h_s/H and decreases with the increase of H/L. Under the same working condition, with the increase of a/b, the horizontal wave force on the structure decreases, the vertical wave force increases, and the dead weight of breakwater increases, so the stability of the breakwater is enhanced. The advantage of semi-elliptical breakwater is that the size relationship between horizontal axis and vertical axis can be designed according to different engineering conditions. If it is laid down with elliptical long axis, it is more suitable for weak foundation bed than semi-circular breakwater with the same depth, so as to be safer and more reliable. If it is erected with a short half axis, it can save materials compared with the half circular breakwater on the premise of preventing the same water depth, and thus reduce the construction cost.