The invention discloses a finish machining device for skin scribing. The finish machining device for skin scribing is provided with a milling template, wherein the milling template is provided with a sliding guide way for a scriber to walk and a scribing slot for skin scribing; one end of the milling template is mounted on a first base through a first adapter plate; the other end of the milling template is mounted on a second base through a second adapter plate; the scriber is provided with a pedestal; one end of the pedestal is an alloy nicking tool mounting part; a sliding guide component which is matched with the sliding guide way is arranged at the bottom of the pedestal; a mounting hole for mounting an alloy nicking tool is formed in the mounting part; an oblong groove is formed in a side wall of the mounting hole; a compression spring is tightened between a root of the alloy nicking tool and the mounting part; a sliding guide cylindrical pin which is matched with the oblong groove is arranged in the middle of the alloy nicking tool; and a tip of the alloy nicking tool is fixedly tightened on the mounting part through a nut. The device is simple in structure and low in manufacturing cost, and has quite high representativeness in the field of skin milling finish machining devices, and one-time high-precision scribing on a metal sheet skin with large curvature can be realized.