The extreme waves generated by the typhoon cause the overtopping of the sloping seawall. However，the existing empirical formulas for calculating the wave overtopping discharge have the applicability. In order to find out the formula for calculating the amount of overtopping of the sloping seawall in Zhoushan area under typhoon weather，we solve the Navier-Stokes and k-ε equations based on the VOF method，establish the numerical wave flume with boundary velocity wave generation and wave damping absorber，build the model of slope seawall in the flume，and simulate the condition of regular waves acting on slope seawall under the typhoon weather by changing the relevant factors affecting wave overtopping discharge. We compare the numerical simulation results with the experimental results of the physical model，analyze the quantitative relationship between each factor and the overtopping coefficient，and propose a new empirical formula for calculating the overtopping coefficient. The results show that the empirical formula presents the logarithmic relationship between the steepness of outburst wave and the wave overtopping discharge. The larger the relative water depth is，the larger the relative height of the dike is，and the smaller the μ′ value is，the smaller the wave overtopping is.