In order to reduce the operation and maintenance cost of the pump, the pump reducer was remanufactured, and the worn double arc gear in the reducer was repaired. On the basis of the existing research, a method based on reverse engineering to extract gear parameters and analyze the gear wear degree was proposed. The 3D laser scanning technology was used to extract the worn gear model data, the gear model was processed in Geomagic Design X software, and the gear module was measured by using the mesh sketch fitting method, and the index circle helix angle parameter was derived. By using a double arc face gear tooth profile equation, the double circular arc gears accurate model was established. The actual engineering double-arc gear shaft parameter extraction and deviation analysis were carried out, and the deviation was analyzed after the solid model was aligned with the scanning model through Geomagic Control X. The results show that compared with manual measurement, by using the proposed method, the measurement difficulty can be reduced while ensuring the measurement accuracy, and the efficiency of the gear measurement can be improved.