The present invention relates to an airplane structure stiffener repair method based on measured data guidance. The method includes: respectively measuring point cloud data on a surface of a structure stiffener and point cloud data on a surface of a to-be-assembled position of a body; respectively extracting all assembly plane features in two point cloud data based on an RANSAC algorithm; performing pre-alignment according to the plane features; performing accurate alignment based on a signed distance constraint according to repair tolerance requirements; and calculating a repair allowance, and generating a machining path to serve as an accurate machining basis. According to the method in the present invention, a repair amount can be accurately calculated by virtue of an alignment algorithm of the signed distance constraint, and an envelope relationship during model matching is met.