The invention belongs to the technical field of 
aviation engineering, and particularly discloses a take-off device for an ornithopter. The take-off device comprises a transverse cable, two 
pulley components, and two drum components driven by outer rotor motors; the two 
pulley components and the two drum components are arranged in symmetry relative an airport 
runway; the transverse cable is sequentially wound around one drum component, the fixed 
pulley component on the same side, the fixed pulley component on the opposite side and the other drum component on the opposite side. The transverse cable crosses the airport 
runway, and the drum components are driven by the outer rotor motors. During take-off, the transverse cable is pulled by a 
towing vehicle to be hung on a padlock mechanism at the front end of the ornithopter, an ornithopter engine and the outer rotor motors are cooperatively started to assist the take-off, and the outer rotor motors help provide the initial speed of the ornithopter, so that the stability of the ornithopter is enhanced, the sliding distance of the ornithopter is shortened, and an ornithopter 
runway is shortened; by the design of the pulley components, the take-off direction can be selected according to the actual 
wind direction; through 
electric power assisted dragging, the fuel consumption is reduced, and the surrounding environmental 
pollution of an airport is reduced.