In this paper, the calculation model of lood distribution of locomotive train roller bearing is set up according to the spesification of the roller bearing constraction and Considering the deformation of inner and outer ring of the bearing and the bearing seat. A diagram of real load distribution is shown, which is result from analysis and calculation through finite element method. Based on this diagram, we have some suggestion and demand on the design of the rigidity of a roller bearing seat. A practical and available load distribution calculation method for roller bearing computer aided optimal design is given.