Abstract: The preparation method of medical Ir-192 afterloading source was studied in this paper. First, The source core was prepared by irradiating iridium wire through high flux reactor, and then the method of argon arc welding seal source shell and source braid was used to prepare Ir-192 afterloading source.The quality test of the Ir-192 afterloading source was carried out. The results showed that the Ir-192 afterloading source had good sealing property, and no leakage orcontamination on the surface. The maximum deviation of activity is less than ±5%. The performance indexes of the products are superior to the industry standards, and achieve the same level of similar products abroad.