One of the main steps in designing submersible vessels is determining the hydrodynamic forces and moments acting on these vehicles. These forces are included inertial forces, added mass, damping, coriolis, propeller and restoring forces and moments. Various methods, such as experimental tests, semi-empirical, analytical method and numerical simulations are used to calculate the hydrodynamic forces. With development of computer sciences, applications of CFD in maritime industries are being feasible and important. Numerical approaches have evolved to a level of accuracy which allows them to be applied to submersibles resistance computations. In this research, damping and added mass coefficients were calculated by numerical simulations. Also Reynolds Averaged Navier-stoks(RANS) simulations were used to solve turbulent equations. In order to calculate the damping and added mass coefficients, uniform straight line test with angle relative to flow direction and linear accelerated motion tests were simulated numerically by commercial Ansys Cfx package. This code is base-on finite volume method. When submarine's movement include attack and drift angles relative to flow direction, the variation of drag coefficient due to this angles are parabolic and the nonlinear damping coefficients may be calculated by drag and lift equations constants. Also linear damping coefficients can be calculated by damping forces and moments diagram versus attack and drift angles. Firstly, numerical simulation was carried out on a sphere to ensure the accuracy of approach and implemented to calculate added mass coefficients. The simulations in this case were combination accelerated and uniform motions in order to investigate the influence of velocity and acceleration values. Also, added mass coefficients were calculated theoretically. Equivalent ellipsoids and strip theory were used in this regards. Equivalent ellipsoids method is base-on potential flow theory and the submarine components were replaced by optimized ellipsoids. When ever mass moment of inertia for various components and replaced ellipsoids were equivalent, the best ellipsoids dimensions were determined. Then linear added mass of each ellipsoid was calculated by lamb's k-factors. Finally total added mass was calculated by summation of the ellipsoids added mass. In strip theory, the added mass of 2D sections was calculated and with integrating over the length of body, total added mass were determined. The assumption of theoretical methods such as disregard viscous effects, time dependent of flow nature caused the accuracy of these methods were decreased and only used to approximate of hydrodynamic coefficients. The numerical and theoretical results were compared with David-Taylor Institution reports and other numerical results. It is noteworthy that non-dimensional results were compared together as well. Good agreements between numerical and experimental results were showed the accuracy of numerical simulations in hydrodynamic problems. Key words : Hydrodynamic coefficients; Numerical simulation; Theoretical method; submarine