Objective To investigate the efficacy and feasibility of CT guided 125I intratumoral implantation in the treatment of lymph node metastasis of retroperitoneal. Methods 20 cases of retroperitoneal lymph node metastasis patients were treated by CT guided 125I seeds implantation in tumor, followed up for 1-24 months to observe the near future curative effect. Results 20 patients were all successfully completed 125I seeds implantation under the guidance of CT without bleeding, infection and other complications. The back pain symptoms in 15 patients began to ease after one week treatment, of which 9 cases were complete remission and 6 patients were partial remission. The volume of lymph nodes of one side of lower extremity edema in 2 patients had reduction. Conclusion CT guided 125I seeds implantation is safe, minimally invasive and curative effect method in the treatment of retroperitoneal lymph node metastasis, and could effectively control the local symptoms.