The invention discloses a distance determination device for measuring a profile of an aero-engine blade. The distance determination device comprises a distance measurement plate for placing a blade and a tenon tooth positioning block that matches the distance measurement plate and is used for installing a blade tenon. The distance measurement plate is one having a bed frame structure and consists of a bottom plate and a plurality of profile segments that are arranged at profiles at the two sides of the bottom plate and match front and rear edge blade backs of the blade; and the positions of the profile segments are consistent with the position, determined by a piece of design paper, of the blade body profile measurement cross section and a profile coordinate point corresponding to a theoretical coordinate point of a to-be-measured blade back profile is designed at one side profile, corresponding to the rear edge of the blade, of each profile segment. The tenon tooth positioning block is provided with two teeth matching a blade tenon top tooth and a root tenon tooth respectively. With the tenon tooth positioning block, the distance between the blade tenon end top surface and the profile segment end surface, approaching the tenon end, of the distance measurement plate is set to be a distance dimension formulated by the design paper.