Rotating machinery which is used in several mechanical system affected by exogenous or endogenous vibration due to unbalance, misalignment and cracks, which leads to generate extra forces on shaft and bearings. This research is dedicated to study the unbalance and dissimilarity of the shaft on the stresses and deflections for a rotor supported by a film of oil bearing. Different rotational speeds (1000 - 4400) rpm and unbalance effects (0.0001-0.0003) m, have been considered. A dynamical model of the system in which the shaft has a rectangular cross – section of (30 x 15) mm2 and with a mass of (6) kg. The parameters of rotor-shaft, which represented by the value of stiffness coefficients and journal bearing represented by stiffness and damping coefficients have been determined using MATLAB/ Simulink software, so that, the reaction forces are calculated. Finite Element Program (ANSYS) has been used for the analysis of the stresses for the shaft and bearings produced eccentricity and rotation.