According to the suitable assumption, the deformation process of extal spline cold rolling is analyzed. By the graphing method, the slip-line field of plastically deforming area in process of extal spline cold rolling is set up. Different friction-conditions are used in different contact areas in order to realistically reflect the actual situation. The unit average pressure on contact surface of the rolling process is solved according to the stress filed theory of slip-line. And the formulae of the rolling-force and rolling-moment are established. The theoretical result is well consistent with the finite element analysis. A theoretical basis is provided for the precise forming process of spline cold rolling and the production of extal splined shafts.