Abstract:Taking SA software as platform, using API laser tracker, the precision coordinate values of the measuring point of a large specialshaped workpiece were gotten. Data processing was done using development software, the 3D model of the workpiece was gotten through unifying coordinate system. Then the 3D model was compared with the theoretical model, processing allowance was analyzed, achieving processing allowance according to blank surface. Finally, more accurate and reasonable allowance for product processing was obtained. It creates convenient for following up product processing.