Objective：To assess and improve the therapeutic effect of interstitial brachytherapy. Methods: A hundred and seventy-three patients with deep brain tumors were treated with interstitial radio therapy through 3 different methods and at 3 different doses in different phases, they were followed up in different periods. Results: No operative death occured in all treated patients. Follow-up of 5-82 months revealed that 3 years survival rate of astrocyte tumors patients of Ⅰ？Ⅱ degrees was 54.5%, the survival rate of 5 years was 38.6%; one year with Ⅲ？Ⅳ degrees was 11.6%, two years was 72.0%, three years was 16.2%. The result of radiology follow-up survey indicated: fifteen cases with tumors completely disappeared (8.7%); 29 cases with tumors dimension shrinking over 80%(16.8%); 81 cases with shrinking 30%？50%(46.8%). Tumors of complete disapperance were intracranial malignant lymphoma, pineal cell tumors, multiform gliblastoma and metastatic tumors etc. Conclusion: To decrease the complications of radiation, improve the effect of treatment, different locations and properties of intracranial tumors should be treated with different radiation doses. The method of ultra-segmentation plus extra-radiation are better.