Today, Submarines have many applications in military activities, oil explorations and oceanography. Prediction of hydrodynamic forces exerting on a submarine, to dynamically control it and to select propulsion system, is one of the important problems in the submarine design. In the present work, viscous, incompressible and turbulent flow around an underwater body is simulated by means of a commercial code which is using finite volume methods. The flow is supposed to be steady and numerical solution of the flow is performed using an unstructured grid with 2800000 cells. In this simulation, the hydrodynamic coefficient of the forces acting on the submarine is estimated in for velocities ranging from 1 m/s to 8.24 m/s and flow angle of attack changes from -12 to +12 degrees. Results of the present work are in good agreement with the results of a marine research center. It shows that submarine drag coefficient in zero angle of attack, decreases when Reynolds number increases and submarine lift coefficient in a constant velocity, increases with an increase in angle of attack. Investigation of flow in the stern region of the submarine shows that fraction wake has a 15% reduction with increasing submarine velocity. Next, flow around a 5-blaeded-propeller is simulated using sliding mesh with unsteady flow consideration. The grid system used for this part consists of 540000 cells that are distributed around the propeller using an unstructured scheme. Simulation is done with two different conditions at the inlet of the submarine propeller. In the first case a uniform inlet flow is used. In the second case the non-uniform flow at the submarine stern which was obtained from our pervious run were used. Results show a good agreement with the results obtained from Boundary Element method and also it shows that the thrust and torque coefficients acting on the propeller decrease with increasing the advance ratio. Study of thrust distribution in the radial directions of the blades reveals that at the outer 40% of the propeller there is about 63.8 percent of generated thrust while at the inner 20% there is only 3.8 percent of the generated thrust. Comparison of the results obtained from a uniform inlet velocity distribution with a non-uniform velocity distribution shows that the hydrodynamic coefficients in the later case are higher than the former one