Objective: To retrospectively analyze the results of treatment outcome by surgery combined with ¹²⁵I brachytherapy and correlative factors of adenoid cystic carcinoma (ACC). Methods: In the study, 75 patients with primary ACC of oral and maxillofacial region were treated by surgery combined with ¹²⁵I seeds brachytherapy. Radical resection or subtotal resection was applied for the tumor. The brachytherapy treatment planning system was used to create implant plans with the prescribed dose of 60 Gy to 120 Gy. The ¹²⁵I seeds were implanted intraoperatively or postoperatively. The regular follow-up was required. The Kaplan-Meier method was used to assess the tumor control rate and the patients’ survival rates. Meanwhile, the Cox regression analysis was used to find out the prognostic factors. Results: Local control rates at the end of 3 and 5 years were as follows: T₁-T₂, 92.2% and 82.0%; T₃-T₄, 82.6% and 82.6%; and overall, 90.0% and 78.8%. The disease-free survival rates were 74.9% and 54.3%, respectively. The overall survival rates for all the patients were 86.0% and 79.6%, respectively at the end of 3 and 5 years and were 91.3% and 91.3% for T₁-T₂ patients vs. 73.9% and 59.7% for T₃-T₄ patients. Distant metastasis-free survival rates at the end of 3 and 5 years were 84.4% and 76.7%, respectively. The distant metastasis-free survival rates at the end of 3 and 5 years were 83.4% and 79.6% with T₁-T₂ lesion compared with 86.0% and 67.8% with T₃-T₄ lesion. According to the COX univariate analysis and multivariate analysis, the risk of local recurrence would be raised by the age. Tumor stage and tumor site were the prognostic factors of the overall survival rates. Conclusion: ¹²⁵I brachytherapy conducted as an adjuvant therapy postoperatively of ACC of oral and maxillofacial region can acquire satisfactory local-regional control, distant metastasis-free survival, disease-free survival and overall survival. Tumors are prone to recur on the older patients. Patients having advanced tumor stage or tumor located in the nasal cavity or sinuses will suffer lower survival rates.