A method for manufacturing the trailing edge ribs and the bearing ribs of trailing edges of aircraft lifting surfaces, in which the trailing edge ribs and the bearing ribs are made by joining simple C-shaped parts and/or simple L-shaped parts so as to obtain the final trailing edge ribs and bearing ribs. The manufacturing of the simple C-shaped parts uses the same tooling both for the trailing edge ribs and the bearing ribs, and the manufacturing of the simple L-shaped parts uses the same tooling both for the trailing edge ribs and the bearing ribs.