[en] In this paper, an optimization method is employed to optimize k-epsilon turbulence model in numerical calculation of ship resistance. The study of conventional ships shows that more than 70 percent of the total resistance is supplied by the surface shear stresses. Therefore, an accurate prediction of the shear stresses at the body plays a critical role in correct design of body curvature and calculation of the flow behavior around it. However, the correct prediction of the shear stresses remarkably depends on the precise modelling of turbulence behavior in the vicinity of wall. There are many semi-empirical coefficients in each turbulence model which are given as general purpose constants. However, these models can be suitably improved for treating special applications such as flow around ships. In this regard, the general semi-empirical coefficients in the k-epsilon turbulence model are suitably combined into an objective function. The objective function is defined based on a comparative weight of numerical solutions with the experimental data. We use Nelder- Mead optimization technique to establish our optimization procedure. The results indicate great improvement in ship resistance calculation. (author)