In order to repair the sprocket of scraper conveyor, the 3D metal printing technology is used to test on 34CrNiMo6 steel plate samples. These samples are carefully examined to acquire metallographic structure, microhardness, indentation and wear resistance. Results show that the hardness is 2~3 times of that of the substrate material, and the wear resistance is also improved dramatically. Subsequently, the employment of this technology to repair a sprocket is carried out. A 3D laser scanner is used to scan a brand new and a worn sprocket to obtain the corresponding point clouds. The data are used to calculate the worn volumes of the sprocket. Software package CATIA is used for modeling and slicing with some newly developed add-on functions. Based on these data, the numerical control programs are established to define and control the repairing paths and parameters of the worn sprocket accurately. 3D printing, milling and test results show that the sprocket is properly repaired, which validates the secondary development, the numerical control programs as well as the developed add-on functions.