Iodine 125 particle implantation is an effective technique for the comprehensive treatment of malignant tumors and is a type of internal brachytherapy. The method involves the implantation of radioactive iodine 125 particles into the tumor or into tissues that may be invaded by the tumor via a minimally invasive (percutaneous puncture) approach or surgery, and also into the lymph nodes where the tumor has metastasized. The decay process of iodine 125 particles emits low-dose gamma rays to irradiate tumor tissues continuously without interruption, which can kill tumor cells and tumor surrounding oxygen-depleted cells at different stages of fission, thus, it can effectively treat tumors and prevent tumor recurrence and metastasis.