Nonlinear effect is of importance to waves propagating from deep water to shallow water.The non-linearity of waves is widely discussed due to its high precision in application.But there are still some problems in dealing with the nonlinear waves in pratice.In this paper,a modified form of mild-slope equation with weakly nonlinear effect is derived by use of the nonlinear dispersion relation and the steady mild-slope equation containing energy dissipation.The modified form of mild-slope equation is convenient to solve nonlinear effect of waves.The model is tested against the laboratory measurement for the case of a submerged elliptical shoal on a slope beach given by Berkhoff et al.The present numerical results are also compared with those obtained through linear wave theory.Better agreement is obtained as the modified mild-slope equation is employed.And the modified mild-slope equation can reasonably simulate the weakly nonlinear effect of wave propagation from deep water to coast.