In order to research the load distribution of a large-size-double row four-point-contact ball bearing, first, the supper element method is used to model the contact between raceways and rolling elements, and the equivalent beam method is used to model the bolt. Then, a simplified finite element model for a large-size double row four-point-contact ball bearing is obtained and its correctness is verified through the results comparison of theoretic algorithm and empirical formula. Finally, the influence of the bolt pretension, the mounting surface flatness and the differences between pitch angles on the load distribution of the bearing is analyzed by the model. The results show that with the increase of the even bolt pretension, the maximum contact load of bearing increases firstly and then slightly decreases. The uneven bolt pretension causes the exacerbated fluctuations of the bearing contact load. The surface flatness errors cause sudden changes of the contact loading distribution. When the degree of pitch-control synchronization is negative, the contact load of bearing increases.