The invention belongs to the technical field of unmanned aerial vehicle structures and particularly relates to a single-axis twin-propeller type structure. An arm meeting electric power large-load transportation and hoisting an article is an important constituent part for expanding and realizing a functionalized unmanned aerial vehicle and comprises a connecting and fixing rack; a long arm is fixed on the connecting and fixing rack; the left end of the long arm is hinged and fixed to the connecting and fixing rack; a motor support sat is fixed at the right end of the long arm and is provided with two sub support seats; and each sub support seat is provided with a motor. The invention further provides an unmanned aerial vehicle comprising the arm. The arm of the unmanned aerial vehicle is hinged to the connecting and fixing rack to better accommodate a plurality of arms of the unmanned aerial vehicle, so that the transportation space is reduced; and in addition, the arm adopts an uppermotor and a lower motor to move along the same central axis; one motor moves clockwise, and the other motor moves anticlockwise, and the reverse twisting force is effectively counteracted through combination of clockwise movement and anticlockwise movement.