The mechanical properties of a traditional steel-cored aluminum strand conductor and a new capacity-expanding and energy-saving conductor for a typical 500 kV transmission line are compared to provide a reference for the conductor lectotype of transmission lines. The study objects are a traditional steel-cored aluminum strand and three new capacity-increasing and energy-saving conductors (a new steel-cored aluminum strand of high conductivity, a new total aluminum alloy aluminum stranded conductor, and a new total aluminum alloy aluminum conductor of medium tenacity). The sag characteristics, icing overload capacity, and load bearing characteristics of these conductors are comprehensively compared and analyzed to obtain the mechanical properties of each conductor. The analytical results show that in the engineering of a 500 kV transmission line, the new steel-cored aluminum strand of high conductivity has the best sag characteristics, icing overload capacity and combined load capacity.