The invention relates to a cross arm safety suspension wire ladder and belongs to the technical field of power transmission and distribution engineering. A ladder body is provided with a U-shaped hanging ring which is hung on a leading wire cross arm through a hand-pulling reversed chain and is provided with a safety rope in a tying mode. A wire hanging hook is arranged below and can hang a leading wire. When a worker maintains a line on line, the worker can go between the cross arm and the leading wire by crossing an insulator and does not tread the insulator or climb the insulator, line maintaining is safe and efficient, labor intensity is low, and the insulator cannot be stained. The cross arm safety suspension wire ladder is used for power transmission line maintaining.