The analysis of bearing characteristics of differential planetary roller screw is carried out based on space meshing theory and Hertz contact theory. Taking into consideration the influence of contact position change caused by the initial meshing point offset between the roller and the screw on the bearing characteristics, the spatial meshing geometry model of the differential planetary roller screw is established, and the meshing point position and principal curvature of the roller and the screw are solved by numerical method. Furthermore, the single roller screw tooth surface accurate load distribution and carrying capacity calculation geometric model are deduced. The calculation results of the model are compared with those of direct stiffness method and the correctness of the presented method is verified. The effects of tooth angle, screw pitch, the number of threads of the roller, and elastic modulus ratio of screw and roller material on the load distribution and bearing capacity of differential planetary roller have been systematically analyzed.