Abstract： Objective To evaluate the role and technical advantages of CT in 125Ⅰseed implantation in the treatment of tumors. Methods CT-guided 125Ⅰ seed implantation in 45 cases of cancer patients treated 57 times in 51 lesions,CT were used to evaluate the progress of lesions after 125Ⅰ seed implantation 1,2,6 months. Results All procedures were once successful and the total effective rate was 74.5% without any serious complications. Fifty CT examinations immediately after implantation showed satisfactorily seeds distribution but seven cases less satisfactorily that include particles overlap,the location is too close to the lesion edge,the larger the radiation cold spots,etc. Follow-up CT reexamination in 1,2 and 6 months demonstrated that CT examinations showed satisfactorily seeds distribution but accurate seeds number,which could be solved by combined with MPR images and the positioning piece. Conclusions CT-guided 125Ⅰ seed implantation treatment of tumors was a safe,reliable and effective minimally invasive treatment. CT in the preoperative treatment of seed implants planning,precise intraoperative guidance,quality assurance and efficacy of postoperative assessment had a greater role and application advantages.