This paper discusses about an optimum hydrodynamic shape of stern of submarine in minimum resistance point of view. Submarines have two major categories for hydrodynamic shape: tear drop shape and cylindrical middle body shape. Here, submarine with parallel (cylindrical) middle body are studied because, the most of naval submarines and ROVs have cylindrical middle body shape. Every hull shape, have three parts: bow, cylinder and stern. This paper wants to propose an optimum stern shape by CFD method and Flow Vision software. Major parameter in hydrodynamic design of stern is wake field (variation of fluid velocity) and resistance. The focus of this paper is on the resistance at fully submerge mode without free surface effects. Firstly, all available equations for the stern shape of submarine are presented. Secondly, for all equations of shapes, CFD analysis has been done. In all models, the velocity, dimensions of domain, diameter, bow shape and the total length (bow, middle and stern length) are constant.