This research presents a theoretical model to analyze the mechanical performance of spherical roller bearings, taking account of the angular and centroidal misalignments between the inner and outer rings. The angular misalignment can be improved by spherical roller bearings self-aligning feature to a certain degree. The interpolation method is used to determine the self-aligning contact angles of the different rollers. The centroidal misalignment is described by the angular and distance deviations. Non-Hertzian contact theory is applied to model and calculate the rollers load-distribution and total contact angles as well as the displacement of the inner ring. The loads of the rollers with the misalignments features and the external loads are included in the equilibrium equations, which is solved by Newton-Raphson method. This research shows spherical roller bearings self-aligning ability can balance the additional bending moment caused by the angular misalignment, which is at the cost of reducing its carrying capacity. But this carrying capacity will be improved to a certain degree by a proper axial load. It also illustrates that any kinds of centroidal misalignments are harmful for the service life of bearings. But the location of the misalignments can be roughly inferred by the external loads and the displacement of the inner ring, which is helpful for spherical roller bearings fault diagnose and elimination.