Method for automatic return flight without GPS (global positioning system) signal

The invention discloses a method for automatic return flight without a GPS (global positioning system) signal. A high-definition camera system is adopted for acquiring ground building video information and storing the ground building video information in an image storage system in a flight process of an airplane; feature information of buildings and terrains is extracted through an image processing algorithm to build an airline information library; ground building images and terrains are also acquired during return flight; the images are processed in a vertical flip manner and compared with the existing airline feature information library; if a plurality of feature buildings or terrains are matched with the airline information library, an airline can be confirmed by a distance measuring device to confirm an instantaneous position of the airplane so as to guide the airplane to realize automatic return flight. The method also can realize automatic return flight without the GPS signal, can be widely applied to actual return flight of various airplanes such as civil airplanes, military airplanes and the like, neither depends on an external control system nor receives data such as the GPS signal and the like, and particularly has the concealed advantages when being applied to the military airplanes.