The invention relates to a dual-arc steel section structure design method, in particular to a structure design method for a transmission tower material in the electric power transmission process. The dual-arc steel section structure of the scheme comprises a vertex angle and a limb plate, wherein the vertex angle is a flat reinforcing plate, and the connecting part of the limb plate and the reinforcing plate is in a relative S-shaped arc section. By adopting the cold-bending technology, a reasonable section shape in the optimized material distribution can be produced according to the need; and with the help of the advantages of the traditional hot-rolled angle steel and by combining the cold-bending technology, the dual-arc steel section structure of the scheme adopts a double S-shaped radian design, the ratio of the free extension length to the thickness of a flange plate can be optimized according to the need, the steel strength reduction due to stable strength is reduced, and the strength utilization ratio of member materials is improved. Compared with the traditional hot-rolled angle steel, the structure has better section characteristics through the arc design of the connecting points and the angle-strengthened protruding cold-bending processing, and the section bearing capacity is greatly improved.