Abstract: This paper aims at proposing an improved numerical model based on the full nonlinear Boussinesq equations for simulating wave breaking in the surf zone.A new formula is proposed based on the concept of surface roller to determine the production term in the k equation of turbulent model.Consequently the eddy viscosity in the Boussinesq equations,which gives the attenuation effect of the waves in the surf zone,can be calculated by solving the k equation.The slot method is used in the model to simulate wave movement in the swash zone.The model is verified by the experimental data in terms of wave height and setup and setdown.Comparison of modeled results with measurements shows a reasonable agreement Modeled results of the turbulent production,the turbulent energy and the dissipation rate of turbulent energy indicate:(1) the turbulent production peaks at the breaking point and decreases gradually as the wave approaches the shoreline;(2) at the incipient regime of wave breaking,the advection and the diffusion effects play an important role in the transport process of the turbulent energy; and(3) as waves approach the shoreline,the turbulent production and the dissipation are almost balanced each other.