Research conclusions: (1) The slope of registration arm relates to the contact wire tension, the first dropper position, the stagger, the span length, the weights of registration arm and clamp, the curve radius and the superelevation of outer rail. (2) From the research presented in this paper, it is concluded when the other main parameters of the catenary are constant, the slope of registration arm of the catenary of 300 km/h or above high-speed railway is not less than 8 degree in straight line section, and in the curve section the slope is not less than 6 degree and the maximum slope is not bigger than 16 degree. (3) To guarantee a good slope of the registration arm, the catenary stagger is ±200 mm in both sections of straight line and curve with large radius, and the distance from the first dropper to the registration point is 5 meter. It can be as the reference to the similar works.